fix(nicknames): handle non-int min/max length settings

Cast the persisted setting to int before handing it to Schema\Str's
minLength/maxLength, and only apply the constraint when the admin has
configured a positive value. An empty field saved from the admin panel
was otherwise stored as '' — triggering a TypeError in PHP's default
weak coercion — and, after the naive cast, coerced to 0, which made
maxLength(0) reject every nickname.

Reveals a gap in Schema\Str: the int-only signature offers no way to
"disable" a length constraint via the condition argument without a
guard at the call site. Keeping the guard local for this RC fix.

Author: imorland

extensions/nicknames/src/Api/UserResourceFields.php

@@ -32,6 +32,13 @@ public function __invoke(): array
             $regex = "/$regex/";
         }
 
+        // Settings are always returned as strings from the DB. Coerce and only
+        // apply the length constraint when the admin has configured a non-zero
+        // value; an empty field saved from the admin panel would otherwise be
+        // stored as '' and cast to 0, making maxLength(0) reject every value.
+        $min = (int) $this->settings->get('flarum-nicknames.min');
+        $max = (int) $this->settings->get('flarum-nicknames.max');
+
         return [
             Schema\Str::make('nickname')
                 ->visible(false)
@@ -43,8 +50,8 @@ public function __invoke(): array
                 // may render as hyperlinks in notification emails.
                 ->rule('not_regex:/[\[\]()<>]/')
                 ->regex($regex ?? '', ! empty($regex))
-                ->minLength($this->settings->get('flarum-nicknames.min'))
-                ->maxLength($this->settings->get('flarum-nicknames.max'))
+                ->minLength($min, $min > 0)
+                ->maxLength($max, $max > 0)
                 ->unique('users', 'nickname', true, (bool) $this->settings->get('flarum-nicknames.unique'))
                 ->unique('users', 'username', true, (bool) $this->settings->get('flarum-nicknames.unique'))
                 ->validationMessages([