Fix undefined variable error in rmgpy/data/kinetics/database.py
Fix undefined variable error in rmgpy/data/kinetics/database.py

chatelak/RMG-Py,nyee/RMG-Py,chatelak/RMG-Py,comocheng/RMG-Py,pierrelb/RMG-Py,comocheng/RMG-Py,nyee/RMG-Py,enochd/RMG-Py,nickvandewiele/RMG-Py,enochd/RMG-Py,nickvandewiele/RMG-Py,pierrelb/RMG-Py