Support applications (like geary) that put an svg into the /usr/share/icons/hicolor/64x64/apps/ directory
Support applications (like Maelstrom) that include the extension in the hicolor name
Support applications (like Anjunta) that include ship the icon in hicoor but also ship pixmaps
trivial: Print the exception if the icon is corrupt
If we set APPSTREAM_DEBUG do not delete the exploded tree
Support applications (like WritRecogn) that include ship only scalable icons
Attempt to read XPM files too

The 1990s called. They want thier icons back.
Never include icons less than 32x32 in size
Support applications (like centerim) that install an icon into /usr/share/icons
Use a less misleading message when the valid icon is too small