Undefined class 'StreamSubscription'. Try changing the name to the name of an existing class

 

I am trying to use the

StreamSubscription class, but it causes the following error and prevents execution.I am trying to use the StreamSubscription class, but it causes the following error and prevents execution.

Undefined class 'StreamSubscription'.
Try changing the name to the name of an existing class, or creating a class with the name 'StreamSubscription'.

It is called an undefined class.

In other words, it doesn't seem to be found. No matter how much it looks, there seems to be no problem.

However, the problem disappeared when the class was re-entered with the keyboard.

When I think about it for a second, the variable is scratched and pasted from another code, and it seems that the problem was probably caused by an error such as an encoding problem. Perhaps it is a bug in VSCode (Visual Studio Code).

In the future, if you encounter this problem when copying and importing code, you may need to type it yourself.