PropertyModifierHook: overridable exportSettings()

fixes #1948

library/Director/Hook/PropertyModifierHook.php

@@ -199,6 +199,11 @@ abstract class PropertyModifierHook
         return $this;
     }
 
+    public function exportSettings()
+    {
+        return (object) $this->settings;
+    }
+
     /**
      * Override this method if you want to extend the settings form
      *

library/Director/Objects/ImportRowModifier.php

@@ -62,7 +62,7 @@ class ImportRowModifier extends DbObjectWithSettings
         $properties =  $this->getProperties();
         unset($properties['id']);
         unset($properties['source_id']);
-        $properties['settings'] = (object) $this->getSettings();
+        $properties['settings'] = $this->getInstance()->exportSettings();
         ksort($properties);
 
         return (object) $properties;

library/Director/Objects/ImportSource.php

@@ -308,6 +308,9 @@ class ImportSource extends DbObjectWithSettings implements ExportInterface
 
     protected function applyPropertyModifierToRow(PropertyModifierHook $modifier, $key, $row)
     {
+        if (! is_object($row)) {
+            throw new InvalidArgumentException('Every imported row MUST be an object');
+        }
         if ($modifier->requiresRow()) {
             $modifier->setRow($row);
         }