running Functional Javascript tests without chromedriver running or accessible causes tests to skip without explanation

I was trying to run Functional Javascript tests with Docksal. Because of the way Docker works, my running chromedriver in a terminal had no effect, so as far as PHPUnit could tell, chromedriver was missing.

However, tests are skipped with no explanation of the problem:

vendor/bin/phpunit docroot/modules/custom/mymodule/tests/src/FunctionalJavascript/MyTest.php
PHPUnit 6.5.14 by Sebastian Bergmann and contributors.

Testing Drupal\Tests\mymodule\FunctionalJavascript\MyTest
S                                                                   1 / 1 (100%)

Time: 2.83 minutes, Memory: 4.00MB

OK, but incomplete, skipped, or risky tests!
Tests: 1, Assertions: 1, Skipped: 1.

There should be a message that explains why the tests are being skipped.