Remove stray brace from compilation error output

An extra brace was inadvertently introduced into a template literal used to format output text in the event of an error
during compilation. This caused the text to end in a pointless `}`

For example:

```
Compilation error: exit status 1}
```

After this change, the output text is as expected:

```
Compilation error: exit status 1
```

Author: per1234

arduino-ide-extension/src/node/core-service-impl.ts

@@ -96,7 +96,7 @@ export class CoreServiceImpl extends CoreClientAware implements CoreService {
         e.details
       );
       this.responseService.appendToOutput({
-        chunk: `${errorMessage}}\n`,
+        chunk: `${errorMessage}\n`,
         severity: 'error',
       });
       throw new Error(errorMessage);