feat: public/private lookup flags, consistency

PluralKit.Bot/Commands/Lists/ContextListExt.cs

@@ -60,7 +60,7 @@ public static class ContextListExt
         // PERM CHECK: If we're trying to access non-public members of another system, error
         if (p.PrivacyFilter != PrivacyLevel.Public && lookupCtx != LookupContext.ByOwner)
             // TODO: should this just return null instead of throwing or something? >.>
-            throw new PKError("You cannot look up private members of another system.");
+            throw Errors.NotOwnInfo;
 
         // Additional fields to include in the search results
         if (ctx.MatchFlag("with-last-switch", "with-last-fronted", "with-last-front", "wls", "wlf"))