[Vala] Valac doesn't shows errors, but assertion `_name != NULL' failed failed

[Tal Hadad <tal_hd hotmail com>]

I'm trying to write some library, using GNU autotools,  but valac complains:
** (valac:23077): CRITICAL **: vala_ccode_identifier_construct: assertion `_name != NULL' failed

** (valac:23077): CRITICAL **: vala_ccode_identifier_construct: assertion `_name != NULL' failed
(yes it's twice)
It just gives me two warning about unused methods, but other than that none.
My valac is 0.12.1. Any one knows why it happens? Is this a known bug?
The work is attached to mail. To reproduce it type in the main dir:
./autogen
make

Tal

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