Do not attempt to free message on NULL return.
Do not attempt to free message on NULL return.

le_hashmap_Get() will return NULL if a key is not found in the hashmap.
In this case, do not attempt to free the message.  This should not
occur, but has been observed in some error scenarios.

Resolves: LE-16024
Change-Id: Ib7d9d8c6fe00d0ff4d7d12b1b4ee28efb6ee80af

legatoproject/legato-af,legatoproject/legato-af,legatoproject/legato-af,legatoproject/legato-af,legatoproject/legato-af,legatoproject/legato-af,legatoproject/legato-af,legatoproject/legato-af,legatoproject/legato-af