veyron/runtimes/google/ipc: Catch test error.
veyron/runtimes/google/ipc: Catch test error.

It seems that tests are occasionally failing in StartCall.
Catch that instead of having the test fail with a nil-dereference later
on.

Change-Id: Ic761ceba8663205e7f38022b47b12e29d729e6fe

vanadium/go.ref,vanadium/go.ref,vanadium/go.ref,vanadium/go.ref,vanadium/go.ref,vanadium/go.ref