illegal_async_generator_return_type
Functions marked 'async*' must have a return type that is a supertype of
'Stream
Description
#The analyzer produces this diagnostic when the body of a function has the
async* modifier even though the return type of the function isn't either
Stream or a supertype of Stream.
Example
#The following code produces this diagnostic because the body of the
function f has the 'async*' modifier even though the return type int
isn't a supertype of Stream:
dart
int f() async* {}Common fixes
#If the function should be asynchronous, then change the return type to be
either Stream or a supertype of Stream:
dart
Stream<int> f() async* {}If the function should be synchronous, then remove the async* modifier:
dart
int f() => 0;