I still have a triangle in the bottom-right corner to resize the textarea (Fx 22, Linux).
Even if I insert `%0A%0D` in the error, the textarea grows.

I tested this by visiting `http://localhost:5555/web/viewer.html?file=..some-insanely-long-non-existent-filename...`.

Only one line is missing, do you experience the same? If so, then I can add some extra pixels and it'll be fixed.