I'm trying to do a simple TCP sever and client in vibe. Quite often when I run my code [1] I get the error in the subject. Here is the full output:

$ dub
Target vibe-d 0.7.21-rc.4 is up to date. Use --force to rebuild.
Target vibetest ~master is up to date. Use --force to rebuild.
Running ./vibe
test
Starting app.Client
Running app.Client
Task terminated with unhandled exception: Assertion failure
core.exception.AssertError@../../../.dub/packages/vibe-d-0.7.21-rc.4/source/vibe/core/core.d(951): Assertion failure
Error executing command run: Program exited with code 1

I'm using:

OS X 10.9.5
DMD 2.066.0
DUB version 0.9.22
vibe-d 0.7.21-rc.4
libevent 2.0.21 from Macports

[1] http://pastebin.com/MsYPDGZG

/Jacob Carlborg