fix: Throw an error on transpile if the package.json main or exports is not set properly

[Devesh36]

/fix #1167

Overview

Changed the transpile command to throw an error instead of warning when package.json main or exports fields are not properly configured to point to the dist/ directory.

---

Behavior Changes

1. Main Field Points Outside dist/

❌ BEFORE

$ cat package.json
{
  "name": "my-package",
  "main": "index.tsx"
}

$ tsci transpile index.tsx

Output:

When using transpilation, your package's "main" field should point inside the `dist/*` directory, usually to "dist/index.js"
Transpiling entry file...
Building ESM bundle...
[... transpilation continues ...]
Transpile complete!

Exit Code: 0 (SUCCESS - continues despite misconfiguration)

---

✅ AFTER

$ cat package.json
{
  "name": "my-package",
  "main": "index.tsx"
}

$ tsci transpile index.tsx

Output:

When using transpilation, your package's "main" field must point inside the `dist/*` directory, usually to "dist/index.js"

Exit Code: 1 (ERROR - stops immediately)

---

2. Missing Both main and exports Fields

❌ BEFORE

$ cat package.json
{
  "name": "my-package",
  "version": "1.0.0"
}

$ tsci transpile index.tsx

Output:

Transpiling entry file...
Building ESM bundle...
[... transpilation continues despite missing fields ...]

Exit Code: 0 (SUCCESS - no validation for missing fields)

---

✅ AFTER

$ cat package.json
{
  "name": "my-package",
  "version": "1.0.0"
}

$ tsci transpile index.tsx

Output:

When using transpilation, your package.json must have either a "main" or "exports" field pointing to the output in the `dist/*` directory

Exit Code: 1 (ERROR - stops immediately)

---

3. Invalid exports Field (NEW - Only In AFTER)

❌ BEFORE

$ cat package.json
{
  "exports": {
    ".": "./lib/index.js",
    "./utils": "./utils.js"
  }
}

$ tsci transpile index.tsx

Output:

Transpiling entry file...
[... transpilation continues with invalid exports ...]

Exit Code: 0 (SUCCESS - no exports validation)

---

✅ AFTER

$ cat package.json
{
  "exports": {
    ".": "./lib/index.js",
    "./utils": "./utils.js"
  }
}

$ tsci transpile index.tsx

Output:

When using transpilation, your package's "exports" field must point to outputs in the `dist/*` directory

Exit Code: 1 (ERROR - validates all export paths)

---

Error Messages Summary

Scenario	BEFORE	AFTER
main outside dist	⚠️ Warning: "should point"	❌ Error: "must point"
Missing main & exports	✅ No validation	❌ Error: "must have either"
Invalid exports paths	✅ No validation	❌ Error: "must point to outputs"
Valid main/exports	✅ Proceeds	✅ Proceeds

---

Implementation Details

Files Modified

1. cli/utils/validate-main-in-dist.ts

   • Changed from console.warn() to throw new Error()
   • Added validation for missing main and exports fields
   • Added new validateExports() helper function
   • Recursive validation for nested export structures

2. tests/cli/transpile/transpile.test.ts

   • Test renamed: "warns when main is outside dist" → "throws error when main is outside dist"
   • Error message updated: "should point" → "must point"
   • New test: "throws error when main and exports are not set"

3. tests/cli/build/build-transpile.test.ts

   • Test renamed: "warns when main is outside dist" → "throws error when main is outside dist"
   • Error message updated: "should point" → "must point"
   • New test: "throws error when main and exports are not set"

Error Handling

Both cli/transpile/register.ts and cli/build/register.ts already have try-catch blocks that catch and properly handle the thrown errors:

try {
  validateMainInDist(projectDir, distDir)
  // ... transpile logic ...
} catch (error) {
  const message = error instanceof Error ? error.message : String(error)
  console.error(message)
  process.exit(1)
}

---

Test Results

Transpile Tests

$ bun test tests/cli/transpile/transpile.test.ts
(pass) transpile throws error when main is outside dist [656.39ms]
(pass) transpile throws error when main and exports are not set [728.92ms]

Build Tests

$ bun test tests/cli/build/build-transpile.test.ts
(pass) build with --transpile throws error when main is outside dist [1465.01ms]
(pass) build with --transpile throws error when main and exports are not set [1549.87ms]

1. Early Error Detection: Catches misconfiguration before spending time on transpilation
2. Clearer Intent: "must point" is stronger and clearer than "should point"
3. Comprehensive Validation: Now validates both main and exports fields
4. Nested Export Support: Recursively validates complex export structures
5. Prevents Package Issues: Ensures published packages will have correct entry points

[Devesh36]

i think the check is failing because of it's a Windows-only test running on macOS

[rushabhcodes]

The test does not run on you device, i think there is a problem in the test or you introduced one

[Devesh36]

The test does not run on you device, i think there is a problem in the test or you introduced one

yaa fixed it ! Did a obvious mistake ;)

[imrishabh18]

You should not be throwing an error for this, it should be a warning how it was before.

The issue lacked context when that was created

[Devesh36]

You should not be throwing an error for this, it should be a warning how it was before.

The issue lacked context when that was created

ok then ! should i close this commit ?