fix: log error message when external JS fails to load (#27837)

Author: Boris-c

lib/extension/externalJS.ts

@@ -193,7 +193,7 @@ export default abstract class ExternalJSExtension<M> extends Extension {
                 fs.renameSync(filePath, `${filePath}.invalid`);
 
                 logger.error(
-                    `Invalid external ${this.mqttTopic} '${extension.name}' was ignored and renamed to prevent interference with Zigbee2MQTT.`,
+                    `Invalid external ${this.mqttTopic} '${extension.name}' was ignored and renamed to prevent interference with Zigbee2MQTT. (${(error as Error).message})`,
                 );
                 // biome-ignore lint/style/noNonNullAssertion: always Error
                 logger.debug((error as Error).stack!);

test/extensions/externalConverters.test.ts

@@ -348,6 +348,7 @@ describe("Extension: ExternalConverters", () => {
             );
             expect(fs.existsSync(filepath)).toStrictEqual(false);
             expect(fs.existsSync(path.join(mockBasePath, "invalid.mjs.invalid"))).toStrictEqual(true);
+            expect(mockLogger.error).toHaveBeenCalledWith(expect.stringContaining("Parse failure: Expected ';', '}' or <eof>"));
         });
     });