From fd8afd2b2e599895cc06269d7b7cddce006929d6 Mon Sep 17 00:00:00 2001
From: Matthias Schmidt <gravatronics@live.com>
Date: Mon, 28 May 2018 20:13:31 +0200
Subject: [PATCH] Ignore `null` as passed value for
 `TSelectionFormField::value()`

See #2509
---
 .../system/form/builder/field/TSelectionFormField.class.php | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/wcfsetup/install/files/lib/system/form/builder/field/TSelectionFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/TSelectionFormField.class.php
index 24d13501cd..fdb25a800c 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/TSelectionFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/TSelectionFormField.class.php
@@ -154,6 +154,12 @@ trait TSelectionFormField {
 	 * @inheritDoc
 	 */
 	public function value($value): IFormField {
+		// ignore `null` as value which can be passed either for nullable
+		// fields or as value if no options are available
+		if ($value === null) {
+			return $this;
+		}
+		
 		if (!in_array($value, $this->possibleValues)) {
 			throw new \InvalidArgumentException("Unknown value '{$value}'");
 		}
-- 
2.20.1