feat: Support .wxtrc config file (#1833)

Co-authored-by: Aaron <aaronklinker1@gmail.com>

packages/wxt/e2e/tests/user-config.test.ts

@@ -139,17 +139,15 @@ describe('User Config', () => {
     ).toBe(true);
   });
 
-  it('should throw error when config file not exist', async () => {
+  it('should not throw error when config file not exist', async () => {
     const project = new TestProject();
     project.addFile(
-      'src/entrypoints/background.ts',
+      'entrypoints/background.ts',
       `export default defineBackground(
         () => console.log('Hello background'),
       );`,
     );
 
-    await expect(
-      project.build({ configFile: 'foo.config.ts' }),
-    ).rejects.toThrowError(/not found/);
+    await project.build({ configFile: 'foo.config.ts' });
   });
 });

packages/wxt/src/core/resolve-config.ts

@@ -50,11 +50,7 @@ export async function resolveConfig(
       configFile: inlineConfig.configFile,
       name: 'wxt',
       cwd: inlineConfig.root ?? process.cwd(),
-      rcFile: false,
     });
-    if (inlineConfig.configFile && metadata.layers?.length === 0) {
-      throw Error(`Config file "${inlineConfig.configFile}" not found`);
-    }
     userConfig = loadedConfig ?? {};
     userConfigMetadata = metadata;
   }