Can't convert PDF into image, because of 'no images defined' error
Solution 1:
You are missing the optional Ghostscript dependency gs - which is not optional if you want to convert a PDF file.
If which gs doesn't resolve to the ghostscript binary (e.g. you have an alias with the same name), edit the path to Ghostscript in delegates.xml.
Solution 2:
You can also try doing:
brew uninstall ghostscriptbrew install ghostscript
That fixed it for me.