Unexpected hinted bb_code_rules code event listener triggered without a hint

[Xon]

Affected version

XF2.3

If you create a code event listener for bb_code_rules, and give it a context hint; then the following will trigger it to be called when it is not expected:

{{ bb_code('test', null, null) }}

Additionally the documentation should be updated to be explicit it is about nullable strings, ie:

<em>\XF\BbCode\RuleSet</em> $ruleSet - The ruleset object being created.
<em>?string</em> $context - A string representing the context of the rule set, usually representing the content type.
<em>?string</em> $subContext - A string representing the sub-context of the rule set. This may not always be provided, but can represent a specific situation (such as "rss").

		$container->factory('rules', function($context, array $params, Container $c)
		{
			$parts = explode(':', $context, 2);
			if (count($parts) == 2)
			{
				$context = $parts[0];
				$subContext = $parts[1];
			}
			else
			{
				$subContext = null;
			}
...

This could be simplified to:

		$container->factory('rules', function($context, array $params, Container $c)
		{
			$parts = explode(':', $context ?? '', 2);
			$context = $parts[0] ?? '';
			$subContext = $parts[1] ?? null;

It is probably a good idea to not pass null into explode as this triggers a warning from php 8.1+