enhace windows list storages case (#2276)

os/windows/local/mode/liststorages.pm

@@ -115,9 +115,9 @@ sub run {
             long_msg => sprintf(
                 "'%s' [size: %s][free: %s][desc: %s][type: %s]",
                 $_->{name},
-                $_->{size},
-                $_->{freespace},
-                $_->{desc},
+                defined($_->{size}) ? $_->{size} : '',
+                defined($_->{freespace}) ? $_->{freespace} : '',
+                defined($_->{desc}) ? $_->{desc} : '',
                 $map_type->{ $_->{type} }
             )
         );
@@ -145,10 +145,10 @@ sub disco_show {
     foreach (@$result) {
         $self->{output}->add_disco_entry(
             name => $_->{name},
-            size => $_->{size},
-            free => $_->{freespace},
+            size => defined($_->{size}) ? $_->{size} : '',
+            free => defined($_->{freespace}) ? $_->{freespace} : '',
             type => $map_type->{ $_->{type} },
-            desc => $_->{desc}
+            desc => defined($_->{desc}) ? $_->{desc} : ''
         );
     }
 }