The code in Pipeline::Transport does not check wether fixers is defined or not. It will just read out the fixers property nonetheless and set a default "undefined" fixer. This will trigger an error in Fixer::Fix because it assumes that there is an "undefined" fixer set, but its file_name property is missing.
The default Fixer "Fix" throws an error "file_name is undefined" when the file_name property is set, without the fixers property:
The code in Pipeline::Transport does not check wether fixers is defined or not. It will just read out the fixers property nonetheless and set a default "undefined" fixer. This will trigger an error in Fixer::Fix because it assumes that there is an "undefined" fixer set, but its file_name property is missing.