Warning: A non-numeric value encountered

When I try to access the dashboard, I am receiving the following errors:

Warning: A non-numeric value encountered in /homepages/25/d736126010/htdocs/clickandbuilds/Direct4Workgear/wp-includes/functions.php on line 74

Warning: Cannot modify header information – headers already sent by (output started at /homepages/25/d736126010/htdocs/clickandbuilds/Direct4Workgear/wp-includes/functions.php:74) in /homepages/25/d736126010/htdocs/clickandbuilds/Direct4Workgear/wp-includes/pluggable.php on line 1296

Warning: Cannot modify header information – headers already sent by (output started at /homepages/25/d736126010/htdocs/clickandbuilds/Direct4Workgear/wp-includes/functions.php:74) in /homepages/25/d736126010/htdocs/clickandbuilds/Direct4Workgear/wp-includes/pluggable.php on line 1299

I cannot access the dashboard at all and the site is being redirected to some spammy thing. I can access via FTP, I’ve disabled plugins, nothing happened, disabled themes, again nothing.
So I went into functions.php to line 74, and this is what I have…

function current_time( $type, $gmt = 0 ) {
	// Don't use non-GMT timestamp, unless you know the difference and really need to.
	if ( 'timestamp' === $type || 'U' === $type ) {
		return $gmt ? time() : time() + (int) ( get_option( 'gmt_offset' ) * HOUR_IN_SECONDS );
	}

	if ( 'mysql' === $type ) {
		$type = 'Y-m-d H:i:s';
	}

	$timezone = $gmt ? new DateTimeZone( 'UTC' ) : wp_timezone();
	$datetime = new DateTime( 'now', $timezone );

	return $datetime->format( $type );
}

Can anybody help me set the timezone so that I can get passed this and also does anyone have suggestions for the dodgy redirect?

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