Angular 2 Exceptions: TypeError: (msg || "").replace is not a function

While performing tdd using the Angular CLI, I have come across this exception a few times. In most cases this is caused by a missing import.  The Angular CLI kicks off a test before an import has been added to the component (or service, etc).  If you have the benefit of an IDE, check that it has not highlighted a problem with one of your imports.

The full exception is:

	17 06 2016 08:46:39.287:WARN [web-server]: 404: /base/dist/traceur
	Missing error handler on `socket`.
	TypeError: (msg || "").replace is not a function
	at /home/dspies/projects/sms/node_modules/karma/lib/reporter.js:45:23
	at onBrowserError (/home/dspies/projects/sms/node_modules/karma/lib/reporters/base.js:58:60)
	at null.<anonymous> (/home/dspies/projects/sms/node_modules/karma/lib/events.js:13:22)
	at emitTwo (events.js:100:13)
	at emit (events.js:185:7)
	at onKarmaError (/home/dspies/projects/sms/node_modules/karma/lib/browser.js:95:13)
	at Socket.<anonymous> (/home/dspies/projects/sms/node_modules/karma/lib/events.js:13:22)
	at emitOne (events.js:95:20)
	at Socket.emit (events.js:182:7)
	at Socket.onevent (/home/dspies/projects/sms/node_modules/socket.io/lib/socket.js:335:8)
	at Socket.onpacket (/home/dspies/projects/sms/node_modules/socket.io/lib/socket.js:295:12)
	at Client.ondecoded (/home/dspies/projects/sms/node_modules/socket.io/lib/client.js:193:14)
	at Decoder.Emitter.emit (/home/dspies/projects/sms/node_modules/component-emitter/index.js:134:20)
	at Decoder.add (/home/dspies/projects/sms/node_modules/socket.io-parser/index.js:247:12)
	at Client.ondata (/home/dspies/projects/sms/node_modules/socket.io/lib/client.js:175:18)
	at emitOne (events.js:90:13)
	at Socket.emit (events.js:182:7)
	at Socket.onPacket (/home/dspies/projects/sms/node_modules/engine.io/lib/socket.js:101:14)
	at emitOne (events.js:90:13)
	at WebSocket.emit (events.js:182:7)
	at WebSocket.Transport.onPacket (/home/dspies/projects/sms/node_modules/engine.io/lib/transport.js:104:8)
	at WebSocket.Transport.onData (/home/dspies/projects/sms/node_modules/engine.io/lib/transport.js:115:8)

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