Handle null dereference

llvm/lib/CodeGen/WinEHPrepare.cpp

if (I->isEHPad())
       State = EHInfo.EHPadStateMap[I];
     EHInfo.BlockToStateMap[BB] = State; // Record state, also flag visiting
 
     if ((isa<CleanupReturnInst>(TI) || isa<CatchReturnInst>(TI)) && State > 0) {
       // Retrive the new State
       State = EHInfo.CxxUnwindMap[State].ToState; // Retrive next State
     } else if (isa<InvokeInst>(TI)) {
       auto *Call = dyn_cast<CallBase>(TI);
+      assert(Call);
       const Function *Fn = Call->getCalledFunction();
       if (Fn && Fn->isIntrinsic() &&
           (Fn->getIntrinsicID() == Intrinsic::seh_scope_begin ||
            Fn->getIntrinsicID() == Intrinsic::seh_try_begin))
         // Retrive the new State from seh_scope_begin
         State = EHInfo.InvokeStateMap[cast<InvokeInst>(TI)];
       else if (Fn && Fn->isIntrinsic() &&
                (Fn->getIntrinsicID() == Intrinsic::seh_scope_end ||
if (isa<CatchPadInst>(I) && isa<CatchReturnInst>(TI)) {
       if (!Filter || !Filter->getName().startswith("__IsLocalUnwind"))
         State = EHInfo.SEHUnwindMap[State].ToState; // Retrive next State
     } else if ((isa<CleanupReturnInst>(TI) || isa<CatchReturnInst>(TI)) &&
                State > 0) {
       // Retrive the new State.
       State = EHInfo.SEHUnwindMap[State].ToState; // Retrive next State
     } else if (isa<InvokeInst>(TI)) {
       auto *Call = dyn_cast<CallBase>(TI);
+      assert(Call);
       const Function *Fn = Call->getCalledFunction();
       if (Fn && Fn->isIntrinsic() &&
           Fn->getIntrinsicID() == Intrinsic::seh_try_begin)
         // Retrive the new State from seh_try_begin
         State = EHInfo.InvokeStateMap[cast<InvokeInst>(TI)];
       else if (Fn && Fn->isIntrinsic() &&
                Fn->getIntrinsicID() == Intrinsic::seh_try_end)
         // end of current state, retrive new state from UnwindMap