Max,
I decided to confirm things for you so I started fresh...
I built two new ESB Projects that use the sendEsbMessag sample.
The runtime errors appeared when I specified the JBoss AS target runtime during project creation.
The runtime errors did not appear (and the appropiate text was logged in log/server.log) when I specified <none> as the JBoss AS target runtime during project creation.
Feel free to contact me directly if you have any questions so we don't clutter this thread - I certainly can be doing something wrong.