Can have non-defined DSs again.

includes/add_datastream.form.inc

@@ -149,7 +149,8 @@ function islandora_add_datastream_form_validate(array $form, array &$form_state)
     $form_state['values']['dsid']
   );
   $file = file_load($form_state['values']['file']);
-  if ($file) {
+  // Only validate extensions if mimes defined in ds-composite.
+  if ($file && $extensions) {
     $errors = file_validate_extensions($file, implode(' ', $extensions));
     if (count($errors) > 0) {
       form_set_error(

includes/mimetype.utils.inc

@@ -73,7 +73,7 @@ function islandora_get_extensions_for_mimetype($mimetype) {
 function islandora_get_extensions_for_datastream(AbstractObject $object, $dsid) {
   module_load_include('inc', 'islandora', 'includes/utilities');
   $datastream_mime_map = islandora_get_datastreams_requirements_from_models($object->models);
-  $mimes = $datastream_mime_map[$dsid]['mime'];
+  $mimes = isset($datastream_mime_map[$dsid]) ? $datastream_mime_map[$dsid]['mime'] : array();
   if (isset($object[$dsid])) {
     $current_mime = $object[$dsid]->mimetype;
     if (!in_array($current_mime, $mimes)) {