PHP Warning: Undefined array key 1 in /www/oremcommx_742/public/wp-c

This code is causing a huge number of warnings
if ( preg_match( '#height=["|\']?([\d%]+)["|\']?#i', $tag, $height_string ) ) {
			if ( ctype_digit( $width_string[1] ) === true ) {
				$args['height'] = $height_string[1];
			}
		}

I think this line should be Replaced:

if ( ctype_digit( $width_string[1] )

with

if ( ctype_digit( $height_string[1] ) === true ) {