In case of UA_EVENT_CALL_TRANSFER_FAILED, UA_EVENT_AUDIO_ERROR the pointer call given as function parameter is de-referenced.

Other ua_event_handler that use information from call will crash with a segfault if there are called after menus ua_event_handler.

It depends on the order of modules initialization. If a module with an ua_event_handler is loaded after menu, the segfault occurs.

Commits that cause the issue:
commit 7b6b8a0
Author: Alfred E. Heggestad alfred.heggestad@gmail.com
Date: Wed Oct 10 17:57:26 2018 +0200

add UA_EVENT_AUDIO_ERROR (ref #539) (#555)

commit 4dd9bc9
Author: juha-h jh@tutpro.com
Date: Tue Oct 30 11:42:29 2018 +0200

pass CALL_EVENT_TRANSFER_FAILED event to handler and handle it in menu module (#567)