type 'Future<bool>' is not a subtype of type 'bool' in type cast 以下是导致错误的源代码: Future<bool> fetchCourses= null) {
final userCollection = await FirebaseFirestore.instance.collection('users').doc(loggedInUser.uid
我收到这个错误"type 'Null‘is not a subtype of type 'List’in type cast“ & “无效参数(onError):Future.catchError的错误处理程序必须返回未来类型的值Xcode -在/Applications/Xcode.app/Contents/Developer.Xcode 13.0,Build version 13A233✗CocoaPods中开发适用于iOS