tracker-results-window: Fixed a bunch of issues
tracker-results-window: Fixed a bunch of issues

- Fixed the hidden category column issue.
- Fixed a crasher from recursively requesting images for files which
  don't exist (race condition)
- Fixed some missing \n from debugging
- Fixed not showing the "no results" label if some SQL errors and
  there are no results.

outofbits/tracker,hoheinzollern/tracker,hoheinzollern/tracker,outofbits/tracker,hoheinzollern/tracker,hoheinzollern/tracker,hoheinzollern/tracker,outofbits/tracker,outofbits/tracker,outofbits/tracker,hoheinzollern/tracker,hoheinzollern/tracker,outofbits/tracker,outofbits/tracker