Real life prevented me from working on this project for a while... and now that I'm back on it I see I left my work in a bad state.
I've mentioned my keen interest in good error reporting. But reporting an error is only helpful if the user (in this case, me) actually looks at the error and does something about it. Ahem.
I have a little website to show my art and facilitate a trickle of sales. It's meant to show pictures of the designs and products. Months ago, I added price tags to the products to emphasize that these are things that can be purchased. When I did that, I broke the handling of my "database" (just a big CSV file, don't tell my employer) for designs, which don't have price information. There were nice clear warning messages being reported and logged, but I didn't notice. For months. This might have even caused some outages as the page generator looked for designs that weren't there.
This was a very quick fix even though I haven't touched the project.