fix(dead-export-finder): harden error handling and add ParseError tests

- workspace-detector: catch only GlobError (not all errors) in readPkgDirs
- workspace-detector: fail with WorkspaceNotFoundError on malformed root
  package.json instead of silently returning empty object
- workspace-detector: use Effect.try instead of try/catch in Effect.gen
- CLI: catch GlobError from scanner.scan, accumulate as warning
- tests: add ParseError tests for both export-parser and import-parser

41 tests passing across 7 test files.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: ryanbas21

packages/dead-export-finder/src/index.ts

@@ -116,7 +116,18 @@ const command = Command.make(
       const parseWarnings: string[] = [];
 
       for (const pkg of allPackages) {
-        const files = yield* scanner.scan(pkg.root, ignoreGlobs);
+        const files = yield* scanner.scan(pkg.root, ignoreGlobs).pipe(
+          Effect.catchTag('GlobError', (e) =>
+            Effect.gen(function* () {
+              const msg = `failed to scan files in ${pkg.root}: ${String(e.cause)}`;
+              parseWarnings.push(msg);
+              if (verbose) {
+                yield* Console.log(`Warning: ${msg}`);
+              }
+              return [] as readonly string[];
+            }),
+          ),
+        );
 
         for (const filePath of files) {
           const sourceResult = yield* fs.readFileString(filePath, 'utf-8').pipe(Effect.either);

packages/dead-export-finder/src/lib/export-parser.test.ts

@@ -2,6 +2,7 @@ import { it } from '@effect/vitest';
 import { expect } from 'vitest';
 import { Effect } from 'effect';
 import { ExportParser, ExportParserLive } from './export-parser.js';
+import { ParseError } from './errors.js';
 
 // ─── helpers ──────────────────────────────────────────────────────────────────
 
@@ -112,3 +113,12 @@ it.effect('parses type exports', () =>
     expect(names).toContain('Bar');
   }),
 );
+
+it.effect('returns ParseError for syntactically invalid source', () =>
+  Effect.gen(function* () {
+    const error = yield* parse('bad.ts', '<<<invalid>>>').pipe(Effect.flip);
+    expect(error).toBeInstanceOf(ParseError);
+    expect(error.filePath).toBe('bad.ts');
+    expect(error.message).toBeTruthy();
+  }),
+);

packages/dead-export-finder/src/lib/import-parser.test.ts

@@ -2,6 +2,7 @@ import { it } from '@effect/vitest';
 import { expect } from 'vitest';
 import { Effect } from 'effect';
 import { ImportParser, ImportParserLive } from './import-parser.js';
+import { ParseError } from './errors.js';
 
 // ─── helpers ──────────────────────────────────────────────────────────────────
 
@@ -96,3 +97,12 @@ it.effect('parses type-only imports', () =>
     expect(symbols[0]?.isDynamic).toBe(false);
   }),
 );
+
+it.effect('returns ParseError for syntactically invalid source', () =>
+  Effect.gen(function* () {
+    const error = yield* parse('bad.ts', '<<<invalid>>>').pipe(Effect.flip);
+    expect(error).toBeInstanceOf(ParseError);
+    expect(error.filePath).toBe('bad.ts');
+    expect(error.message).toBeTruthy();
+  }),
+);

packages/dead-export-finder/src/lib/workspace-detector.ts

@@ -128,7 +128,7 @@ export const WorkspaceDetectorLive = Layer.effect(
       resolveWorkspaceGlobs(path, root, globs).pipe(
         Effect.flatMap((dirs) => Effect.all(dirs.map((d) => readPackageInfo(fs, path, d)))),
         Effect.map((infos) => infos.filter((p): p is PackageInfo => p !== null)),
-        Effect.catchAll(() => Effect.succeed([] as PackageInfo[])),
+        Effect.catchTag('GlobError', () => Effect.succeed([] as PackageInfo[])),
       );
 
     const detect = (cwd: string): Effect.Effect<WorkspaceResult, WorkspaceNotFoundError> =>
@@ -151,13 +151,10 @@ export const WorkspaceDetectorLive = Layer.effect(
 
         if (hasRootPkg) {
           const raw = yield* fs.readFileString(rootPkgPath, 'utf-8').pipe(Effect.orDie);
-          const rootPkg: Record<string, unknown> = (() => {
-            try {
-              return JSON.parse(raw) as Record<string, unknown>;
-            } catch {
-              return {};
-            }
-          })();
+          const rootPkg = yield* Effect.try({
+            try: () => JSON.parse(raw) as Record<string, unknown>,
+            catch: () => new WorkspaceNotFoundError({ cwd }),
+          });
 
           // npm / yarn workspaces
           const workspaces = rootPkg['workspaces'];