Invalid argument on CCK fields unrelated to Node type

Having installed the latest dev version to test that the recent commits (including my own #564680: Add support for bulk rebuilds of derivative files in Image module) were working, I am getting the following error repeated over 20 times when creating an image node:

warning: Invalid argument supplied for foreach() in C:\Documents and Settings\admin\My Documents\My Websites\btomcc\sites\all\modules\filefield_paths\filefield_paths.module on line 551

I have added two CCK fields to Image on the system in question but I think the errors are generated for fields that aren't associated with my Image content type.

Specifically I think the problem is in this code:

          // Get CCK fields.
          if (module_exists('content')) {
            $cck = content_fields(NULL, $node->type);
            foreach ($cck as $name => $field) {
              if ($field['type'] == 'text') {
                foreach ($node->{$name} as $key => $value) {
                  if (isset($node->{$name}[$key]['value'])) {
                    $fields["{$name}_{$key}"] = &$node->{$name}[$key]['value'];
                  }
                }
              }
            }
          }

As I understand the comments in content.module, content_fields(NULL, $node->type) does NOT return all fields for just $node->type because the first parameter is NULL. It returns all CCK fields in my system (and there are quite a few).

Then when the line foreach ($node->{$name} as $key => $value) { is executed, $name can be a field name that is not instantiated on $node at all.

I will see whether it is enough just to test whether $node->{$name} is set before attempting to apply foreach to it.