More detailed error message when can't find node in database tree.
More detailed error message when can't find node in database tree.

This helps you figure out what's wrong (eg. you're trying to find radical
corrections for a [C] atom).
chatelak/RMG-Py,faribas/RMG-Py,faribas/RMG-Py,comocheng/RMG-Py,enochd/RMG-Py,nickvandewiele/RMG-Py,comocheng/RMG-Py,KEHANG/RMG-Py,enochd/RMG-Py,chatelak/RMG-Py,pierrelb/RMG-Py,nickvandewiele/RMG-Py,pierrelb/RMG-Py,KEHANG/RMG-Py,nyee/RMG-Py,nyee/RMG-Py