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https://github.com/bknd-io/bknd/
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Cameron Pak
4defc4d1e7
Replace untyped catch blocks and scattered process.exit() with errore tagged errors and error-as-values pattern. Compile-time safety for error handling paths. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
91 lines
3.1 KiB
Markdown
91 lines
3.1 KiB
Markdown
# Proactive Error Handling with errore in `run.ts`
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Ref: https://errore.org/
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## Goal
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Replace scattered `process.exit()`, untyped `catch (e: any)`, and inline error handling in `run.ts` with errore's error-as-values pattern. Compile-time exhaustive error handling via `matchError` in a single top-level `action()`.
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## Constraints
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- `makeAppFromEnv` and `makeConfigApp` are exported — **do not change their return types**
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- `platform.ts` (`startServer`, `serveStatic`, `getConfigPath`) — **unchanged this PR**
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- Keep it simple: errors defined in `run.ts`, not a separate file
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## Phase 1: Add errore dependency
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- `app/package.json`: add `"errore"` to dependencies
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- Run install
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## Phase 2: Define tagged errors in `run.ts`
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```ts
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import errore from "errore"
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class ConfigLoadError extends errore.createTaggedError({
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name: "ConfigLoadError",
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message: "Failed to load config: $reason",
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}) {}
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class NeedsBunError extends errore.createTaggedError({
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name: "NeedsBunError",
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message: "Config requires Bun runtime",
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}) {}
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class NeedsTypeStrippingError extends errore.createTaggedError({
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name: "NeedsTypeStrippingError",
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message: "Node $version needs --experimental-strip-types for .ts config",
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}) {}
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class ReexecFailedError extends errore.createTaggedError({
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name: "ReexecFailedError",
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message: "Re-exec failed: $reason",
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}) {}
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```
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## Phase 3: Refactor internal functions to return errors
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### `loadConfigFile` → `ConfigLoadError | NeedsBunError | NeedsTypeStrippingError | CliBkndConfig`
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- Use `errore.tryAsync` to wrap `import()`
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- On catch: detect Bun requirement → `NeedsBunError`
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- On catch: other failure → `ConfigLoadError`
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- Before import: check `needsTypeStripping()` → `NeedsTypeStrippingError`
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### `reexecWithTypeStripping` / `reexecUnderBun` → `ReexecFailedError | never`
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- Success: `process.exit(0)` (unavoidable — must stop parent after child completes)
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- Failure: return `ReexecFailedError` instead of `process.exit(1)`
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- Caller decides how to handle failure
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### `makeAppFromEnv` internal flow (return type unchanged)
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- Internally use error-as-values from `loadConfigFile`
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- On `NeedsBunError` / `NeedsTypeStrippingError`: call re-exec, handle `ReexecFailedError`
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- On `ConfigLoadError`: `console.error` + `process.exit(1)`
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- Keep exported signature: `Promise<App>` (exits on unrecoverable errors)
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### `action()` — cleaner top-level
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- `makeAppFromEnv` handles its own error cases internally (since we can't change its return type)
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- `action()` stays thin: call `makeAppFromEnv` → `startServer`
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## Phase 4: Verify
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- No behavior change for end users
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- All `catch (e: any)` replaced with typed errore patterns
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- `process.exit(1)` consolidated to fewer, explicit locations
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- Re-exec failure paths return typed errors before exiting
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## Files Changed
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| File | Change |
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|---|---|
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| `app/package.json` | add `errore` dep |
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| `app/src/cli/commands/run/run.ts` | tagged errors, refactored error flow |
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## Commit Message
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```
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refactor(cli): use errore for typed error handling in run command
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Replace untyped catch blocks and scattered process.exit() with
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errore tagged errors and error-as-values pattern. Compile-time
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safety for error handling paths.
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```
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