When trying to create images with the devel generate module and having the module Image Field Caption enabled, you will get an error. This patch should resolve the issue.

image_field_caption_devel_generate.patch

Index: image_field_caption.module
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- image_field_caption.module  (date 1379394208000)
+++ image_field_caption.module	(revision )
@@ -213,6 +213,10 @@
       $items = (array) $entity->{$field_name}[$langcode];
       $delta_count = 0;
       foreach ($items as $delta => $item) {
+        // Make sure we have a value.
+        if (!isset($item['image_field_caption'])) {
+          continue;
+        }
         // We now know we have someting to insert.
         $do_insert = TRUE;
         $record = array(