Plugin Checker Deactivation Causes Error in CLI Command

[mukeshpanchal27]

During QA testing, it was discovered that if the Plugin Checker is deactivated and the CLI command npm run wp-env run cli -- wp plugin check {plugin} --require=./wp-content/plugins/plugin-check/cli.php is executed, it shows an error. The error is related to the behaviour discussed in the following comment on GitHub: #194 (comment). As a result of this finding, the decision was made to throw an error when anyone attempts to use the CLI command while the Plugin Checker is not activated.

Proposed Solution:
To address the issue, the possible code changes need to be added to the cli.php file. However, due to the cli.php file running early in WordPress, certain functions cannot be used there. As a workaround, the necessary code has been added to the includes/CLI/Plugin_Check_Command.php file.

Steps to Reproduce:

1. Install any plugin that you want to check.
2. Deactivate the "Plugin Checker" from Admin Panel > Plugins.
3. Execute the following CLI command:

   npm run wp-env run cli -- wp plugin check {plugin} --require=./wp-content/plugins/plugin-check/cli.php
   

   Replace {plugin} with the slug of the plugin you want to check.
4. Observe the error that occurs.

Expected behaviour:
After applying the changes from the pull request, the CLI command should display the error message: Error: plugin-check/plugin-check.php is not active. when attempting to use it while the Plugin Checker is not activated.

Checklist:

• I agree to follow this project's Code of Conduct.

[swissspidy]

Overall looks good.

Reminds me to look into #153 soon

[felixarntz]

Thanks @mukeshpanchal27, LGTM, would be great if you could incorporate @swissspidy's suggestion.

[mukeshpanchal27]

Thank you, @swissspidy, for the suggestion. We will definitely take a look at item 153 as soon as possible. Your input is appreciated!