We should have structure tests that make sure all of the entries in $wgHooks and $wgExtensionFunctions are valid callbacks.
The previous comments don't explain who or what (task?) exactly this task is stalled on ("If a report is waiting for further input (e.g. from its reporter or a third party) and can currently not be acted on"). Hence resetting task status.
(Smallprint, as general orientation for task management: If you wanted to express that nobody is currently working on this task, then the assignee should be removed and/or priority could be lowered instead. If work on this task is blocked by another task, then that other task should be added via Edit Related Tasks... → Edit Subtasks. If this task is stalled on an upstream project, then the Upstream tag should be added. If this task requires info from the task reporter, then there should be instructions which info is needed. If this task needs retesting, then the TestMe tag should be added. If this task is either out of scope and nobody should ever work on this, or nobody else managed to reproduce the problem described in this task, then this task should have the "Declined" status. If the task is valid but should not appear on some team's workboard, then the team project tag should be removed while the task has another active project tag.)