message: Handle None input tensors in lowering if they are eventually not used
  Summary:
  Pull Request resolved:
  Corner case.
diff: @@ -230,7 +230,10 @@ class Lowerer:
  == LowerPrecision.FP16
  ):
  module.half()
  - inputs = tuple(x.half() if x.dtype == torch.float32 else x for x in inputs)
  + inputs = tuple(
  + x.half() if x is not None and x.dtype == torch.float32 else x
  + for x in inputs
  + )
  pm = self.lower_pass_manager_builder.build_lower_pipeline(inputs)
  lower_result = pm(module)
  