+### Event: 'error'
+
+* `err` {Error Object} the error.
+
+Emitted when:
+
+1. The process could not be spawned, or
+2. The process could not be killed, or
+3. Sending a message to the child process failed for whatever reason.
+
+Note that the `exit`-event may or may not fire after an error has occured. If
+you are listening on both events to fire a function, remember to guard against
+calling your function twice.
+
+See also [`ChildProcess#kill()`](#child_process_child_kill_signal) and
+[`ChildProcess#send()`](#child_process_child_send_message_sendhandle).
+