I've messed with metadata.calibre enough to see the effects
My comment was because I looked to see what the line of code reported in the error was doing. It was opening the SQLite database on the device. If the metadata.calibre was a problem, the error should have happened a long time before this when it was being read. Or a little afterwards when it was being updated.
But, you have reminded me of something:
plac: As theducks said, metadata.calibre is used by calibre to match the books between the calibre library and the device. If you have sent epubs with multiple authors to the Glo using calibre, they probably won't be shown as on the device anymore. You need to find the books in the device list, right click on one of the books and select "Match book to library". You are then prompted to search for the book. When you find it, select it and press OK. When you have done this for all books, right click on the device button and select "Update cached metadata on device". This will update the metadata.calibre so that the books will be correctly shown on the device in the future.