fix(test): throw errors instead of warnings for critical patch failures

Convert warnings to errors for critical patches in patchVitestBrowserPackage:
- vendor-aliases plugin injection
- exclude list patching
- BrowserContext alias patching

This ensures build fails immediately if vitest code changes break our patches,
rather than producing confusing runtime errors for users.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: Brooooooklyn

packages/test/build.ts

@@ -1203,7 +1203,10 @@ async function patchVitestBrowserPackage() {
     content = content.replace(pluginArrayPattern, `$1\n    ${vendorAliasesPlugin},$2`);
     console.log('  Injected vitest:vendor-aliases plugin');
   } else {
-    console.log('  Warning: Could not find browser plugin array to inject vendor-aliases');
+    throw new Error(
+      'Failed to inject vendor-aliases plugin in @vitest/browser/index.js: pattern not found. ' +
+        'This likely means vitest code has changed and the patch needs to be updated.',
+    );
   }
 
   // 2. Patch exclude list to add native deps
@@ -1225,7 +1228,10 @@ async function patchVitestBrowserPackage() {
     content = content.replace(excludePattern, excludeReplacement);
     console.log('  Patched exclude list with native deps');
   } else {
-    console.log('  Warning: Could not find exclude array to patch');
+    throw new Error(
+      'Failed to patch exclude list in @vitest/browser/index.js: pattern not found. ' +
+        'This likely means vitest code has changed and the patch needs to be updated.',
+    );
   }
 
   // 3. Remove include patterns that reference bundled deps
@@ -1255,7 +1261,10 @@ async function patchVitestBrowserPackage() {
     );
     console.log('  Patched BrowserContext to handle package aliases');
   } else {
-    console.log('  Warning: Could not find BrowserContext pattern to patch');
+    throw new Error(
+      'Failed to patch BrowserContext in @vitest/browser/index.js: pattern not found. ' +
+        'This likely means vitest code has changed and the patch needs to be updated.',
+    );
   }
 
   await writeFile(browserIndexPath, content, 'utf-8');