Fix undefined property error

src/Mapping/BindResult.php

@@ -49,21 +49,24 @@ public static function fromFormErrorSequence(FormErrorSequence $formErrorSequenc
 
     public function isSuccess()
     {
-        return null === $this->formErrors;
+        return null === $this->formErrorSequence;
     }
 
     /**
      * @return mixed
      */
     public function getValue()
     {
-        Assertion::same(null, $this->formErrors, 'Value can only be retrieved when bind result was successful');
+        Assertion::same(null, $this->formErrorSequence, 'Value can only be retrieved when bind result was successful');
         return $this->value;
     }
 
     public function getFormErrorSequence() : FormErrorSequence
     {
-        Assertion::notNull($this->formErrors, 'Form errors can only be retrieved when bind result was not successful');
+        Assertion::notNull(
+            $this->formErrorSequence,
+            'Form errors can only be retrieved when bind result was not successful'
+        );
         return $this->formErrors;
     }
 }