Missing return statement for nullable return typeDRT-W1244

The analyzer produces this diagnostic when a method or function can implicitly return null by falling off the end. While this is valid Dart code, it's better for the return of null to be explicit.

Example

The following code produces this diagnostic because the function f implicitly returns null:

String? f() {}

Common fixes

If the return of null is intentional, then make it explicit:

String? f() {
  return null;
}

If the function should return a non-null value along that path, then add the missing return statement:

String? f() {
  return '';
}