Properly check for valid lon/lat

	my $lat        = $self->param('lat');

	my $backend_id = $self->param('backend') // 0;

	if ( not $lon or not $lat ) {

	if (

		not(    defined $lon

			and defined $lat

			and $lon =~ m{^ \d+ [.]? \d* $}x

			and $lat =~ m{^ \d+ [.]? \d* $}x )

	  )

	{

		$self->render(

			json => { error => "Invalid lon/lat (${lon}/${lat}) received" } );

		return;