Empty ignore containers setting causes JS errors.

Problem/Motivation

Leaving the "Skip over these elements" setting (under "Inclusions & exclusions" on the settings page) blank results in JS errors:

Uncaught (in promise) Error: Syntax error, unrecognized expression: [aria-hidden], [aria-hidden] *, [aria-hidden], [aria-hidden] * *, [aria-hidden] *, [aria-hidden] *, [aria-hidden], [aria-hidden] * * *, [aria-hidden] * *, [aria-hidden] * *, [aria-hidden] *, [aria-hidden] * *, [aria-hidden] *, [aria-hidden] *, [aria-hidden], .search-results * * * *, .search-results * * *, .search-results * * *, .search-results * *, .search-results * * *, .search-results * *, .search-results * *, .search-results *, .search-results * * *, .search-results * *, .search-results * *, .search-results *, .search-results * *, .search-results *, .search-results *, .search-results, #comment-form * * * *, #comment-form * * *, #comment-form * * *, #comment-form * *, #comment-form * * *, #comment-form * *, #comment-form * *, #comment-form *, #comment-form * * *, #comment-form * *, #comment-form * *, #comment-form *, #comment-form * *, #comment-form *, #comment-form *, #comment-form, .text-format-wrapper * * * *, .text-format-wrapper * * *, .text-format-wrapper * * *, .text-format-wrapper * *, .text-format-wrapper * * *, .text-format-wrapper * *, .text-format-wrapper * *, .text-format-wrapper *, .text-format-wrapper * * *, .text-format-wrapper * *, .text-format-wrapper * *, .text-format-wrapper *, .text-format-wrapper * *, .text-format-wrapper *, .text-format-wrapper *, .text-format-wrapper, * * *, * *, * *, *, * *, *, *, , * *, *, *, , *,

There are a series of these errors, with the selectors getting bigger and bigger, but the problem seems to be the double commas from adding a comma even if ed11yContainerIgnore is empty.

Steps to reproduce

Install 1.0.11 on Drupal 9.2.13, enter "main" for the "Check content in this container" setting, leave others default. Load a page of content.

Proposed resolution

Attached patch checks for empty ed11yContainerIgnore before adding comma.

Remaining tasks

Please review.

User interface changes

N/A

API changes

N/A

Data model changes

N/A