Deleting molecules can make errors difficult to fix

[cnlbob]

When deleting a molecule, the other panels (reactions, release, etc) are not updated reflecting that deletion. This leads to MCell runtime errors which can be difficult to deduce.

Even worse, when the deletion leaves no remaining molecules, those panels aren't even drawn so it's difficult to know that there's a reaction or release site referring to the missing molecule.

The workaround is to re-create the missing molecule (or at least some other molecule) then the panels will be redrawn showing the error and they can be corrected.