fix: guard validation helpers against undef IP

lib/Urupam/Utils.pm

@@ -58,6 +58,7 @@ sub sanitize_url {
         return undef if $authority =~ /[\s\x00-\x1F\x7F]/;
 
         my $hostport = ( split /\@/, $authority )[-1];
+        return undef unless defined $hostport && length $hostport;
         my $host_raw;
         if ( $hostport =~ /^\[(.+)\](?::\d+)?$/ ) {
             $host_raw = $1;

lib/Urupam/Validation.pm

@@ -71,6 +71,7 @@ sub is_valid_url_length {
 
 sub _is_valid_ipv4 {
     my ( $self, $ip ) = @_;
+    return 0 unless defined $ip;
     return 0 unless $ip =~ /^(\d+)\.(\d+)\.(\d+)\.(\d+)$/;
     my ( $a, $b, $c, $d ) = ( $1, $2, $3, $4 );
     return