Squeak WAVNCController>>#renderContentOn: needs to test existence of a vnc server before asking if it is running

[timrowledge]

The current version of WAVNCController>>#renderContentOn: crashed because the RFBServer class return nil if there is no running instance. A simple change to test for nil first solves this -

renderContentOn: html
	html heading: 'VNC Server'.
	self serverInstance
		ifNil: [self renderStartOn: html]
		ifNotNil:
			[self isServerRunning
				ifTrue: [ self renderStopOn: html ]
				ifFalse: [ self renderStartOn: html ]].
	html heading: 'UI Process'.
	self uiProcess isSuspended
		ifFalse: [ self renderSuspendOn: html ]
		ifTrue: [ self renderResumeOn: html ]

The RFBServer class also needs a small fix to provide an #isRunning method, but that is easy to solve and already committed in https://source.squeak.org/ss/RFB-tpr.23

[marschall]

Wouldn't it be better to do the nil check in #isServerRunning?

[timrowledge]

Yes, I do believe it would.
Something like

isServerRunning
	^ self serverInstance
		ifNil: [false]
		ifNotNil: [:srv| srv isRunning]

would probably be snesible. Or even 'sensible'.