undefined_super_operator

The operator '{0}' isn't defined in a superclass of '{1}'.

The analyzer produces this diagnostic when an operator is invoked on super, but no superclass of the enclosing declaration defines that operator.

The following code produces this diagnostic because the superclass A doesn't define the operator +:

class A {}
​
class B extends A {
  int m() => super + 0;
}

If the operator isn't defined, then add it to a superclass:

class A {
  int operator +(int other) => 0;
}
​
class B extends A {
  int m() => super + 0;
}

Otherwise, remove the invocation.