currently, the output background command handler prematurely
returns with an error if the background file cannot be accessed.
It should only error if user did not provide fallback color.
closes#8556
Changes
- Introduce variables to avoid uneccessary writing on output members
- Log a debug message when fallback is being used over inaccessible
file
- Always parse the background color and swaynag warn if it is incorrect
- when updating output member variables, free previous values
- add cleanup label and goto it if `strdup` fails
- Move output->member initializations to before parsing fallback, Also
free and init output->background as well
d75dfba0e7