Fixed a NPE

Clover/app/src/main/java/org/floens/chan/ui/activity/ImagePickActivity.java

@@ -63,6 +63,7 @@ public class ImagePickActivity extends Activity {
                 final Uri uri = data.getData();
 
                 Cursor returnCursor = getContentResolver().query(uri, null, null, null, null);
+                if (returnCursor != null) {
                     int nameIndex = returnCursor.getColumnIndex(OpenableColumns.DISPLAY_NAME);
                     returnCursor.moveToFirst();
                     String name = "image";
@@ -104,6 +105,9 @@ public class ImagePickActivity extends Activity {
                             }
                         }
                     }).start();
+                } else {
+                    Toast.makeText(this, R.string.image_open_failed, Toast.LENGTH_LONG).show();
+                }
             }
         }
     }