Just encountered a bug with STM that might be related to the recent update. I'm on Unity 2019.2.8f1.
The error is Mesh.uv is out of bounds. The supplied array needs to be the same size as the Mesh.vertices array, and it points to line 4324 of SuperTextMesh.cs.
For some reason this only happens on one particular dialogue box when it gets rebuilt (e.g. if it attempts to auto-read or if I change something in the Unity editor). It doesn't happen on the other boxes. I could try to find what makes this particular STM object different from the others, but do you have any clues for what to look for?
Oddly, this happens even if I delete the STM component and replace it with a fresh one