I "fixed" it temporarily by editing rpg_core.js to have createLinearGradient() have arguments (0,0,1,1) but it resulted in NaN health but not crashing until after returning to Elmgar and traveling to a new map. So the real work around was to retry that battle until she used the alternate move and then also win the fight and now I'm past the 4th dungeon.
So this game had me hooked enough to not only deal with an RPG Maker game but work around that crash so I guess that's a ringing endorsement from me.