Puzzlum.NET TRK_BulkLink()

function trk_bulklink( $in = '' )
{
    $pattern = '/(.*){{(.*)}}(.*)/';
    for( ; preg_match_all( $pattern, $in, $matches ) ; )
    {
        trk_echo3('matches',$matches);
        $params = explode( '|', $matches[ 2 ] );

        $temp =
        '<a href="?'. $params[ 1 ] .
        '='. $params[ 2 ] .
        '">'.
        ( isset( $params[ 3 ] ) ? ( '<img src="' . $params[ 3 ] . '">' ) : '' ) .
        ( ( isset( $params[ 3 ] ) && isset( $params[ 4 ] ) ) ? ( '<br>' ) : '' ) .
        ( isset( $params[ 4 ] ) ? ( '<img src="' . $params[ 3 ] . '">' ) : '' ) .
        '</a>';

        $in = str_replace( $matches[ 0 ], $temp, $in );

    }
}


===

Fatal error: Uncaught TypeError: explode(): Argument #2 ($string) must be of type string, array given in C:\xampp8\htdocs\puzzlum.net\php\trk swaps.php:9 Stack trace: #0 C:\xampp8\htdocs\puzzlum.net\php\trk swaps.php(9): explode('|', Array) #1 C:\xampp8\htdocs\puzzlum.net\index.php(131): trk_bulklink('<style>{{font.m...') #2 {main} thrown in C:\xampp8\htdocs\puzzlum.net\php\trk swaps.php on line 9

Line 9:
$params = explode( '|', $matches[ 2 ] );