Fix a crash when getting the multiparm size, but the asset is not valid
Fix a crash when getting the multiparm size, but the asset is not valid

pokyfudywise/HoudiniEngineForMaya,sideeffects/HoudiniEngineForMaya,pokyfudywise/HoudiniEngineForMaya,sideeffects/HoudiniEngineForMaya,sideeffects/HoudiniEngineForMaya,pokyfudywise/HoudiniEngineForMaya