Step 1: First of all click "Add/Edit Configurations" as like image 1:
Step 2: Choose "Flutter" from configuration list and select your Dart entrypoint path according to your flavor then give a name and allow dart support for this project. See on Image 2, 3 and 4:
N.B: In this step you may need to setup your dart sdk path. If you get warned for "dart sdk not found in specified location" then just click on "fix" and select your dart sdk path.