Runtime-error notes app

hello everyone i'm making a notes app and i'm aiming for for when save button pressed it it saves to documents but when i press the save button all it says is, runtime error, no error problem how do i fix that, please someone help.

Screenshot of error please
Relevant blocks image please


here it is i read google to do it

OK

Android version ?
Filescope setting ?
Error message ?

android 4.1.2
legacy
runtime-error
warning runtime error (no error problem)