Welp, washing machine error code; failed to drain. Pump refused to run, just made a humming noise, so I figured that it must be busted.

Cleaned out the filter anyway, and what do you know, it pumps fine again? Still not quite sure why that helped - there were no obvious blockages in the filter, other than some gunk buildup. I guess the gunk provided too much friction for the pump to run?

Either way, that turned out to be easier to fix than expected, especially as initially the washing machine was full of water (but it turned out that putting the hose in a bucket was enough to drain it, even without a working pump). Just a bit messy water-wise.