Fix remaining tests

Author: jderusse

FormFieldRegistry.php

@@ -57,7 +57,7 @@ public function remove($name)
         $target = &$this->fields;
         while (\count($segments) > 1) {
             $path = array_shift($segments);
-            if (!\array_key_exists($path, $target)) {
+            if (!\is_array($target) || !\array_key_exists($path, $target)) {
                 return;
             }
             $target = &$target[$path];
@@ -80,7 +80,7 @@ public function &get($name)
         $target = &$this->fields;
         while ($segments) {
             $path = array_shift($segments);
-            if (!\array_key_exists($path, $target)) {
+            if (!\is_array($target) || !\array_key_exists($path, $target)) {
                 throw new \InvalidArgumentException(sprintf('Unreachable field "%s"', $path));
             }
             $target = &$target[$path];