polyline_add_stops: catch missing lat/lon in route

	for my $stop ( @{$route} ) {

		for my $polyline_index ( 0 .. $#{$polyline} ) {

			my $pl = $polyline->[$polyline_index];

			if ( not( defined $stop->[2]{lat} and defined $stop->[2]{lon} ) ) {

				my $err

				  = sprintf(

"Cannot match uploaded polyline with the  journey's route: route stop %s (ID %s) has no lat/lon\n",

					$stop->[0], $stop->[1] // 'unknown' );

				die($err);

			}

			my $dist

			  = $distance->distance_metal( $stop->[2]{lat}, $stop->[2]{lon},

				$pl->[1], $pl->[0] );