Don't show message for ellipsis

[davidwagner]

The exception

AttributeError: 'ellipsis' object has no attribute 'show'

triggers a custom response that is not helpful. The custom response is:

It seems we have a AttributeError. AttributeErrors are usually because of:

1. Trying to get an attribute that doesn't exist, or misspelled, i.e a = Table().with_columns("Column 1", data) then calling a.num_row instead of a.num_rows

This is not helpful. In this case, we should not show any custom message.