Check for no action task so we don't add an undefined page

[mattwire]

Overview

Partial from #20940 which contains the actual fix for the crash (there's a lot of PHP notice fixes there too but the actual fix is a small change so extracted here for ease of review).

This was found following release 1.2 of exportpermissions extension which supports disabling export/print/pdf/labels tasks. It turns out that disabling all of these can cause the advanced search to fail because some "modules" do not have any search tasks - see progressivetech/net.ourpowerbase.exportpermission#6.

Specifically Activities and Mailings trigger a "Network error" when you click the accordion to expand the search criteria because when there are no tasks defined a "null" page gets added which then triggers a require_once('.php') here https://github.com/civicrm/civicrm-core/blob/master/CRM/Core/Controller.php#L452 because $className is not defined.

Before

When a search task has no actions (eg. Activity, Mailings) and it is expanded in Advanced Search it crashes.

After

All tasks can be disabled and everything continues working!

Technical Details

Comments

[civibot]

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[eileenmcnaughton]

@mattwire so looking at this the 'original sin' is that (for example) Activity_SearchMachine_Search calls

$this->addSequentialPages($this->_pages, $action);

with invalid data in $this->_pages

That bad data seems to come from one of the places you identified as serving up enotices = activityTask::getTask

It doesn't actually seem like like that getTask function is called from anywhere else so I think we can cleanup the enotice in a way that stops it adding invalid pages - #20951

[mattwire]

Closing in favour of #20951 #20989