I found that in a default skeleton user directory in Elementary 5 (based on Ubuntu bionic), there is no final newline in the .bashrc file, which instead finishes with the word 'esac' which is the end of a case statement.

Pybin's default editing behaviour therefore causes this error...

bash: /home/cefn/.bashrc: line 171: syntax error near unexpected token `PATH="/home/cefn/.local/bin:$PATH"'
bash: /home/cefn/.bashrc: line 171: `esacexport PATH="/home/cefn/.local/bin:$PATH"'

This is easily resolved by putting a newline after the word 'esac' but it would be better if pybin preceded the edit performed by its 'put' behaviour with a newline to be sure this doesn't happen.