Fix empty column name validation in ExprTk editor

[cyril-acquah80]

Removes empty column skip from parse_expression_strings in @finos/perspective. This allows validate_expressions to validate any empty columns

Fixes #2268

[finos-cla-bot]

Thank you for your contribution and Welcome to our Open Source Community!

To make sure your pull request is accepted successfully, we ask all our open source contributors to sign a Contributor License Agreement; having reviewed our contributor list, we require a CLA for the following people : (@cyril-acquah80).

In order to sign a CLA with FINOS, just submit a Pull Request with a simple change to this file (adding an empty line, or some random text at the bottom); this will trigger the EasyCLA bot, which will post a comment to the Pull Request stating whether all PR contributors are covered by FINOS CLA; if not covered, the bot will post instructions on how to sign the CLA.

Thanks once again for your contribution. Let us work with you to make the CLA process quick, easy and efficient so we can move forward with reviewing and accepting your pull request. Feel free to email help@finos.org for any questions.

cc @TheJuanAndOnly99 @mcleo-d

[finos-admin]

@cla-bot[bot] check

[finos-cla-bot]

The cla-bot has been summoned, and re-checked this pull request!

[texodus]

Thanks for the PR! Looks good!

In the future, we generally require tests to accompany bug fixes please. There are many available examples to choose from. Since this PR adds no new code, it's fair to make an exception and rely on the existing tests to assert that this behavior was unnecessary.