test(remix): Surface build output and upload details in source map e2e

The cross-check assertion failed with no indication of why: the build
script swallowed the plugin's debug output, and the assertion reported
neither the client chunk names nor the uploaded ones.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Author: chargome

dev-packages/e2e-tests/test-applications/remix-sourcemaps/assert-build.ts

@@ -96,7 +96,13 @@ for (const chunk of chunks) {
   crossCheckedChunks++;
 }
 
-assert.ok(crossCheckedChunks > 0, 'Expected at least one uploaded chunk to cross-check debug IDs against');
+assert.ok(
+  crossCheckedChunks > 0,
+  'Expected at least one uploaded chunk to cross-check debug IDs against.\n' +
+    `Client chunks:      ${JSON.stringify(chunks.map(chunk => path.basename(chunk)))}\n` +
+    `Uploaded JS names:  ${JSON.stringify([...uploadedJsFiles])}\n` +
+    `Uploaded JS urls:   ${JSON.stringify(debugIdPairs.map(pair => pair.jsUrl))}`,
+);
 console.log(`${crossCheckedChunks} chunk(s) ship a debug ID that was uploaded\n`);
 
 console.log('All remix source map assertions passed!');

dev-packages/e2e-tests/test-applications/remix-sourcemaps/package.json

@@ -3,7 +3,7 @@
   "sideEffects": false,
   "type": "module",
   "scripts": {
-    "build": "node start-mock-sentry-server.mjs & remix vite:build > .tmp_build_stdout 2> .tmp_build_stderr; BUILD_EXIT=$?; kill %1 2>/dev/null; exit $BUILD_EXIT",
+    "build": "node start-mock-sentry-server.mjs & remix vite:build > .tmp_build_stdout 2> .tmp_build_stderr; BUILD_EXIT=$?; kill %1 2>/dev/null; cat .tmp_build_stdout .tmp_build_stderr; exit $BUILD_EXIT",
     "clean": "npx rimraf node_modules pnpm-lock.yaml",
     "test:build": "pnpm install && pnpm build",
     "test:assert": "pnpm tsx assert-build.ts"