DrupalDefaultEntityController invalid argument supplied for foreach
The 2nd argument for node_load_multiple() is an array of conditions; currently you're providing a boolean so when the buildQuery function tries to iterate over the variable you get a warning.

The 3rd argument is to reset the cache (I guess that's what you're trying to do), so the call should be:

$nodes = node_load_multiple($subscription_nids, array(), TRUE);