Fallback to default opener when selected

Fixes #115141

src/vs/workbench/contrib/externalUriOpener/common/externalUriOpenerService.ts

@@ -200,7 +200,7 @@ export class ExternalUriOpenerService extends Disposable implements IExternalUri
 		}
 
 		if (typeof picked.opener === 'undefined') {
-			return true;
+			return false; // Fallback to default opener
 		} else if (picked.opener === 'configureDefault') {
 			await this.preferencesService.openGlobalSettings(true, {
 				revealSetting: { key: externalUriOpenersSettingId, edit: true }