Operation queue deadlock condition

[sgraesser17]

The operation queue will deadlock if cancelAllOperations is called on the queue before all operations have executed. The culprit is in the start method

guard !isCancelled else { finish() return }

The state value will be .ready which will cause the finish method to never change the state to .finished. Thus, causing a deadlock.

You can either update the guard statement to manually set the state to .finish.
Or, change the finish method to not check for the isExecuting state.

[wibosco]

@sgraesser17 thanks for pointing it out, I'll have a think about it and update the project to avoid this