Possible error introduced on 3.39.0

[zespadanal]

When upgrading from v3.38.0 to 3.39.0, we are getting a runtime error:

TypeError: Cannot read properties of undefined (reading 'columns')

After doing some debug, we found out that this is caused on file validateExistingBlockIsIdentical.js, on function validateExistingBlockIsIdentical, where table and tableLocales are undefined.

This happens on the second time it finds a block with the same name in traverseFields.js, in line 343, but on the first round the buildTable function has not returned.

This happens in our code, where we have a block where we use a pattern following this discussion #8741.

This is probably related to fixing issue #12414.