Use async app picker in IPC API to avoid UI freeze

Without this, the rest of the UI visually freezes (boxes repeating if
the dialog is dragged around) while the file selector is open.

src/index.ts

@@ -614,13 +614,16 @@ const ipcHandler = <A, R>(fn: (...args: A[]) => R) => (
     }
 };
 
-ipcMain.handle('select-application', ipcHandler(() => {
-    return dialog.showOpenDialogSync({
+ipcMain.handle('select-application', ipcHandler(async () => {
+    const result = await dialog.showOpenDialog({
         properties:
         process.platform === 'darwin'
             ? ['openFile', 'openDirectory', 'treatPackageAsDirectory']
             : ['openFile'],
-    })?.[0];
+    });
+
+    if (!result || result.canceled) return undefined;
+    else return result.filePaths[0];
 }));
 
 // Enable the default context menu