[quant][fx][fix] Add additional checks when tracing back during maybe share output observer function
Summary:
Currently in `maybe_make_input_output_share_observers` we trace back from a node to find the activation_post_process
of the input node, we have internal use case which would error out during tracing back, this PR is adding a guard
during this process to return False early when the node doesn't have any input
Test Plan:
not sure when this would happen, verify within the internal test case
Reviewers:
Subscribers:
Tasks:
Tags:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/75650
Approved by: https://github.com/vkuzo
