Error Handling
affaan-m/ECC
Patterns for robust error handling across TypeScript, Python, and Go.
defineErrors from wellcrafted: variant factories, extractErrorMessage, InferErrors/InferError, call site patterns.
Custom licenceAuto-check passed
Install Define Errors
$ npx skills add EpicenterHQ/epicenter --skill define-errors -a claude-codeProject install by default; add -g for ~/.claude/skills/.
$ gh skill install EpicenterHQ/epicenter define-errors --agent claude-codeProject scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).
$ git clone --depth 1 https://github.com/EpicenterHQ/epicenter.git skills-src && mkdir -p .claude/skills && cp -r skills-src/.agents/skills/define-errors .claude/skills/define-errors && rm -rf skills-srcUse ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.
Claude Code skills documentation · loads skills from .claude/skills/
Install the "define-errors" agent skill from https://github.com/EpicenterHQ/epicenter/tree/main/.agents/skills/define-errors into .claude/skills/define-errors/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "define-errors", then confirm the skill loads.Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$skill-installer install https://github.com/EpicenterHQ/epicenter/tree/main/.agents/skills/define-errorsType this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.
$ npx skills add EpicenterHQ/epicenter --skill define-errors -a codexProject install goes to .agents/skills/; add -g for ~/.codex/skills/.
$ gh skill install EpicenterHQ/epicenter define-errors --agent codexProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/EpicenterHQ/epicenter.git skills-src && mkdir -p .agents/skills && cp -r skills-src/.agents/skills/define-errors .agents/skills/define-errors && rm -rf skills-srcUse ~/.agents/skills/ instead of .agents/skills for a personal install.
Codex skills documentation · loads skills from .agents/skills/
Install the "define-errors" agent skill from https://github.com/EpicenterHQ/epicenter/tree/main/.agents/skills/define-errors into .agents/skills/define-errors/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "define-errors", then confirm the skill loads.Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add EpicenterHQ/epicenter --skill define-errors -a cursorProject install goes to .agents/skills/; add -g for ~/.cursor/skills/.
$ gh skill install EpicenterHQ/epicenter define-errors --agent cursorProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/EpicenterHQ/epicenter.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/.agents/skills/define-errors .cursor/skills/define-errors && rm -rf skills-srcUse ~/.cursor/skills/ instead of .cursor/skills for a personal install.
Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/
Install the "define-errors" agent skill from https://github.com/EpicenterHQ/epicenter/tree/main/.agents/skills/define-errors into .cursor/skills/define-errors/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "define-errors", then confirm the skill loads.Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gemini skills install https://github.com/EpicenterHQ/epicenter.git --path .agents/skills/define-errors--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.
$ npx skills add EpicenterHQ/epicenter --skill define-errors -a gemini-cliProject install goes to .agents/skills/; add -g for ~/.gemini/skills/.
$ gh skill install EpicenterHQ/epicenter define-errors --agent gemini-cliProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/EpicenterHQ/epicenter.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/.agents/skills/define-errors .gemini/skills/define-errors && rm -rf skills-srcUse ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.
Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/
Install the "define-errors" agent skill from https://github.com/EpicenterHQ/epicenter/tree/main/.agents/skills/define-errors into .gemini/skills/define-errors/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "define-errors", then confirm the skill loads.Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gh skill install EpicenterHQ/epicenter define-errorsInstalls for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).
$ npx skills add EpicenterHQ/epicenter --skill define-errors -a github-copilotProject install goes to .agents/skills/; add -g for ~/.copilot/skills/.
$ git clone --depth 1 https://github.com/EpicenterHQ/epicenter.git skills-src && mkdir -p .github/skills && cp -r skills-src/.agents/skills/define-errors .github/skills/define-errors && rm -rf skills-srcUse ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.
GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/
Install the "define-errors" agent skill from https://github.com/EpicenterHQ/epicenter/tree/main/.agents/skills/define-errors into .github/skills/define-errors/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "define-errors", then confirm the skill loads.GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add EpicenterHQ/epicenter --skill define-errors -a opencodeOpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.
$ gh skill install EpicenterHQ/epicenter define-errors --agent opencodeProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/EpicenterHQ/epicenter.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/.agents/skills/define-errors .opencode/skills/define-errors && rm -rf skills-srcUse ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.
OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/
Install the "define-errors" agent skill from https://github.com/EpicenterHQ/epicenter/tree/main/.agents/skills/define-errors into .opencode/skills/define-errors/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "define-errors", then confirm the skill loads.OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
Facts
- Skill name
define-errors- GitHub stars
- 4.8k
- Token cost
- ~3.2k tokens
- SKILL.md length
- 989 words
- Files
- 1
- Skills in repo
- 64
- Repo updated
- First seen
- Licence
- Custom licence
At a glance
defineErrors from wellcrafted: variant factories, extractErrorMessage, InferErrors/InferError, call site patterns.
- Works in 5 steps: Simple variant: no input, static message → Variant with structured fields: message… → Variant with cause: extractErrorMessage… → …
- Creating error types
- SKILL.md covers Import, Core Rules, Patterns and Type Extraction, plus 5 more sections
- Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md
What it does
Define Errors is an agent skill from EpicenterHQ/epicenter. defineErrors from wellcrafted: variant factories, extractErrorMessage, InferErrors/InferError, call site patterns. Use when creating error types or reviewing error patterns.
Its SKILL.md is about 3.2k tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.
The repository describes itself as: Open-source, local-first apps.
When your agent uses it
- Creating error types
- Reviewing error patterns
Example prompts
- “Use the define-errors skill to defineerror from wellcrafted: variant factories, extractErrorMessage, InferErrors/InferError, call site patterns”
- “/define-errors”
Workflow steps
5 steps, taken from the step headings in SKILL.md.
- Simple variant: no input, static message
- Variant with structured fields: message computed from input
- Variant with cause: extractErrorMessage inside the factory
- Multiple variants in one object: discriminated union built-in
- Domain errors with specific operation failures
What it can do on your machine
Read from SKILL.md and the folder at commit f9441c8. It shows what the files ask for, not the result of running them.
Tool permissions
Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.
From allowed-tools in the SKILL.md frontmatter.
Runs code
No scripts in the folder and no shell commands in SKILL.md (its code samples are typescript).
From the folder's file list and the shell code blocks in SKILL.md.
Network
No URLs in SKILL.md.
From URLs in SKILL.md, links to its own repository left out.
Credentials
Names no API keys, tokens, secrets or passwords.
From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.
Context cost
Define Errors loads about 3.2k tokens when it runs. Until then it costs about 47 tokens; SKILL.md has 989 words of instructions outside code blocks.
Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.
Safety
Auto-check passed
The automated check found no risky patterns in SKILL.md.
Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.
SKILL.md
Its licence (Custom licence) doesn't allow us to republish the file, so here is its outline and opening line. It has 989 words (~3,164 tokens).
“Ground API claims in the official wellcrafted-dev/wellcrafted source and tests for Epicenter's installed version. This skill owns variant construction, naming, fields, and type extraction. error-handling owns catch adaptation and Result consumption; logging owns diagnostic severity and sinks.”
- name
- define-errors
- metadata.author
- epicenter
- metadata.version
- 3.1
Files
Just SKILL.md in .agents/skills/define-errors of EpicenterHQ/epicenter.
Open the folder on GitHubat commit f9441c8
Compare with similar skills
Define Errors next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.
| Skill | Stars | Used in | Tokens | Auto-check | Licence | Repo updated |
|---|---|---|---|---|---|---|
| Define Errors this skillEpicenterHQ/epicenter | 4.8k | — | ~3.2k | Automated safety check: Pass | Custom licence | |
| Error Handlingaffaan-m/ECC | 274k | 1 repos | ~2.7k | Automated safety check: Pass | MIT | |
| Error Handlingthedaviddias/Front-End-Checklist | 74k | — | ~416 | Automated safety check: Pass | MIT | |
| Error Handlingaffaan-m/ECC | 274k | — | ~2.4k | Automated safety check: Pass | MIT | |
| N8n Error Handlingsickn33/agentic-awesome-skills | 47k | 1 repos | ~4.9k | Automated safety check: Pass | MIT | |
| Error Handling Patternswshobson/agents | 40k | 10 repos | ~1k | Automated safety check: Pass | MIT |
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Questions about Define Errors
What does Define Errors do?
defineErrors from wellcrafted: variant factories, extractErrorMessage, InferErrors/InferError, call site patterns. Define Errors is an agent skill from EpicenterHQ/epicenter. defineErrors from wellcrafted: variant factories, extractErrorMessage, InferErrors/InferError, call site patterns.
When should I use Define Errors?
Define Errors fits situations like: creating error types; reviewing error patterns.
How do I install Define Errors in Claude Code?
Run `npx skills add EpicenterHQ/epicenter --skill define-errors -a claude-code`. Or copy the skill folder (.agents/skills/define-errors in EpicenterHQ/epicenter) into .claude/skills/define-errors in your project. Claude Code loads it when a task matches its description.
How do I install Define Errors in Codex?
Run `npx skills add EpicenterHQ/epicenter --skill define-errors -a codex`. Or copy the skill folder (.agents/skills/define-errors in EpicenterHQ/epicenter) into .agents/skills/define-errors in your project. Codex loads it when a task matches its description.
Can I use Define Errors in Cursor, Gemini CLI or GitHub Copilot?
Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add EpicenterHQ/epicenter --skill define-errors -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/define-errors, .gemini/skills/define-errors, .github/skills/define-errors and .opencode/skills/define-errors in your project.
What does Define Errors need to run?
SKILL.md names no scripts, command-line tools or credentials: Define Errors is instructions for the agent only.
Does Define Errors access the network?
SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.
Is Define Errors safe to install?
Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.
What licence does Define Errors use?
Define Errors has a licence file (the repository's licence) that doesn't match a standard licence. Read it on GitHub before reusing the skill.
How many tokens does Define Errors use?
About 3.2k tokens (SKILL.md is roughly 13k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.
What are the alternatives to Define Errors?
Skills that share tags, products or a category with Define Errors: Error Handling (affaan-m/ECC, 274k stars), Error Handling (thedaviddias/Front-End-Checklist, 74k stars), Error Handling (affaan-m/ECC, 274k stars) and N8n Error Handling (sickn33/agentic-awesome-skills, 47k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.
Who maintains Define Errors?
EpicenterHQ (a GitHub organization) maintains it in EpicenterHQ/epicenter, which has 4,818 GitHub stars. The repository holds 64 skills in this directory. The repository was last updated on October 7, 2026.
Source: EpicenterHQ/epicenter on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.