"Couldn't find entity in Gel images" shown when changing background
When updating image background subtraction, I am always getting
"Couldn't find entity in Gel images"
in the status bar. Probably we just change the image object and the update signal doesn't work in the on_update method (https://gitlab.com/iocbio/gel/-/blob/bbf5a6992d5174c871f93757a2f3f8168760b936/iocbio/gel/gui/models/table_model.py#L313)