Internal exception for discriminant generalization failures due to type errors.
def Lean.Meta.splitTarget? (mvarId : MVarId) (splitIte : Bool := true) (useNewSemantics : Bool := false) :
Splits an if-then-else of match-expression in the goal target.
If useNewSemantics is true, the flag backward.split is ignored. Recall this flag only affects the split of if-then-else expressions.