Steps to replicate the issue (include links if applicable):

• Run phan with the new (unreleased) plugin from 2efea9f989697f2e09e91430438ca56b8277f640 in the CampaignEvents extension

What happens?:
Phan reports issue in file src\FrontendModules\EventDetailsParticipantsModule.php

Found usage of isset() on expression $centralUser that appears to be always set. isset() should only be used to suppress errors. Check whether the expression is null instead. See https://w.wiki/98zs

		try {
			$centralUser = $this->centralUserLookup->newFromAuthority( $authority );
			$curUserParticipant = $this->participantsStore->getEventParticipant( $eventID, $centralUser, true );
		} catch ( UserNotGlobalException $_ ) {
			$curUserParticipant = null;
		}
[...]
		$otherParticipants = $this->participantsStore->getEventParticipants(
			$eventID,
			$otherParticipantsNum,
			null,
			null,
			null,
			$showPrivateParticipants,
			isset( $centralUser ) ? [ $centralUser->getCentralID() ] : null
		);

The variable maybe set from the first line of a try/catch block, but when an exception is thrown from the first line, the variable is unset.
Even without isset() phan does not report issue about "possibly undefined", so this could be an upstream issue as well.

What should have happened instead?:
No issue should be found.

It would be correct to report an issue about isset() when $centralUser is set before the try block.