Error: The superclass, 'Diagnosticable', has no unnamed constructor that takes no arguments.

[jianboy]

Target dart2js failed: Exception: ../panache_ui/lib/src/screens/editor/controls/color_picker/color_slider.dart:1101:9:
Error: The superclass, 'Diagnosticable', has no unnamed constructor that takes no arguments.
  const GradientSliderThemeData({
        ^^^^^^^^^^^^^^^^^^^^^^^
Error: Compilation failed.

[GabrielVander]

Same error when attempting to run the repo locally

[zzqo]

Replace extends with with，example:class GradientSliderThemeData with Diagnosticable