unnecessary_null_aware_operator_on_extension_on_nullable

Unnecessary use of a null-aware operator to invoke an extension method on a nullable type.

The analyzer produces this diagnostic when a null-aware operator is used to invoke an extension method on an extension whose type is nullable.

The following code produces this diagnostic because the extension method m is invoked using ?. when it doesn't need to be:

extension E on int? {
  int m() => 1;
}

int? f(int? i) => i?.m();

If it isn't a requirement not invoke the method when the receiver is null, then remove the question mark from the invocation:

extension E on int? {
  int m() => 1;
}

int? f(int? i) => i.m();