Error: System.ArguementOutofRangeException

I created a new test project.
I wanted to try creating a new class object.
I created a new objected which inherited from “Pawn”.
I did not add anything to this new class just saved it and clicked “Compile” on the editor.

I instantly got this crash
ERROR: System.ArgumentOutOfRangeException. Index was out of range.
Parameter name startindex
at System.String LastIndexOf( char value, int32 startindex, int32 count)

no clue what that is seeing as i have not messed with anything of the system.