[5.1] Finder: Allow finder plugins to output spaces

[Hackwar]

Pull Request for Issue #43000 .

Summary of Changes

Finder plugins should not generate any output when being run. If they create output, we expect this to be the output of notices, errors or warnings from PHP directly. This check has been added in 5.0, however some finder plugins out there seem to generate output, most likely from switching between PHP and HTML context. This PR makes this a bit less strict by allowing spaces and new line characters as output. I consider this an acceptable compromise.

Testing Instructions

Codereview

Link to documentations

Please select:

• Documentation link for docs.joomla.org:

• No documentation changes for docs.joomla.org needed

• Pull Request link for manual.joomla.org:

• No documentation changes for manual.joomla.org needed

[Quy]

I have tested this item ✅ successfully on af165ba

---

_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/43093.}

[viocassel]

I have tested this item ✅ successfully on af165ba

---

_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/43093.}

[Quy]

RTC

---

_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/43093.}

[Quy]

RTC

---

_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/43093.}

[35grain]

For anyone stumbling on this before 5.1 is released. These were the symptoms that lead me to this fix in my case:

• The useful message A "finder" plugin has had an error. in everything.php log.
• The error Error An error has occurred while fetching the JSON data: HTTP 502 status code. Bad gateway. in the Smart Search Indexer modal.

[bembelimen]

Thx