@gaaclarke

When running pigeon on a class containing a function without named return type, it throws the mysterious error:

Null check operator used on a null value

This is due to https://github.com/flutter/packages/blob/db9d8c247b77f6c7ad072e09a5fe705a184f8bb2/packages/pigeon/lib/pigeon_lib.dart#L744
Especially as this does not seem to be documented anywhere, it would be critical for user-friendliness to print a proper error message, saying unnamed return types is not supported. rather than throwing an null exception.