It is possible to receive FastDatapathCryptoInitSARemote control plane
message before Confirm'ing a connection. In such case, resetting
heartbeatTimer leads to null pointer dereference, as the timer is
initialized during Confirm'ation.
In this situation, skipping the reset is non-harmful, because
Confirm'ing will reset it.
NB: the reset to 0 should only happen after establishing the connection
on both ends.