fix: close any instance that does not have the lock

src/apps/main/main.ts

@@ -54,6 +54,12 @@ import { setCleanUpFunction } from './quit';
 import { stopSyncEngineWatcher } from './background-processes/sync-engine';
 import { Theme } from '../shared/types/Theme';
 
+const gotTheLock = app.requestSingleInstanceLock();
+
+if (!gotTheLock) {
+  app.quit();
+}
+
 Logger.log(`Running ${packageJson.version}`);
 
 Logger.log('Initializing Sentry for main process');