mixin_of_non_class
Classes can only mix in mixins and classes.
Description
#The analyzer produces this diagnostic when a name in a with clause is
defined to be something other than a mixin or a class.
Example
#The following code produces this diagnostic because F is defined to be a
function type:
dart
typedef F = int Function(String);
class C with F {}Common fixes
#Remove the invalid name from the list, possibly replacing it with the name of the intended mixin or class:
dart
typedef F = int Function(String);
class C {}