aws iot returns MQTT_RX_BUFFER_TOO_SHORT_ERROR when a bad key is created in shadow (CA-91)

[sosaucily]

If I set a key name in the aws iot shadow and that key had not been previously registered with the aws_iot_shadow_register_delta command, the it returns a -32 MQTT_RX_BUFFER_TOO_SHORT_ERROR error. This was very misleading and took quite some time to debug, probably could be something more meaningful.

Tip, make sure to call aws_iot_shadow_yield after this and restart the aws_iot_shadow_yield loop.