Check is_callable parent methods before invoke

src/View/ViewableData.php

@@ -7,6 +7,7 @@
 use InvalidArgumentException;
 use IteratorAggregate;
 use LogicException;
+use ReflectionObject;
 use SilverStripe\Core\ClassInfo;
 use SilverStripe\Core\Config\Config;
 use SilverStripe\Core\Config\Configurable;
@@ -155,13 +156,22 @@ public function __get($property)
     public function __set($property, $value)
     {
         $this->objCacheClear();
-        if ($this->hasMethod($method = "set$property")) {
+        $method = "set$property";
+
+        if ($this->hasMethod($method) && !$this->isPrivate($this, $method)) {
             $this->$method($value);
         } else {
             $this->setField($property, $value);
         }
     }
 
+    private function isPrivate(object $class, string $method): bool
+    {
+        $class = new ReflectionObject($class);
+
+        return $class->getMethod($method)->isPrivate();
+    }
+
     /**
      * Set a failover object to attempt to get data from if it is not present on this object.
      *