Linux – Where is the Cinnamon LookingGlass log

I run Linux Mint 17.1. When I log in I get a Cinnamon notification saying:

Problems during Cinnamon startup

Cinnamon started successfully, but one or more applets, desklets or extension failed to load.

Check your system log and the Cinnamon LookingGlass log for any issues. You can disable the offending extension(s) in Cinnamon Settings to prevent this message from occurring. Please contact the developer.

Sure enough, when I checked the Desklets settings, there was an extension marked with "error".

Out of curiosity, I tried to look for the log message mentioned in the notification to no avail. There were no relevant messages in /var/log/syslog and I could not find the LookingGlass log.

This is what I've tried:

dmesg | grep -i cinnamon
grep -i cinnamon /var/log/syslog
find /var/log -iname "*cinnamon*"
find /var/log -iname "*glass*"
find /var/log -iname "*looking*"