Rider: https://www.jetbrains.com/lp/rider-unreal/
It’s free right now. Probably paid in the future. I don’t know if you can use clang with it. It works like you’d expect an IDE to work, and it’s specifically made for Unreal.
It’s difficult to tell without you linking the code / class causing the error.
How did you go about creating your current pawn subclass?
To create a subclass of Pawn, you just go to your UE4 editor and create a new c++ class and pick APawn as your parent class.