A class method cannot call other class methods without explicitly using "this." to get at the instance pointer. The error messages do not make it obvious what the problem is. It appears that the method calls are being elaborated as normal task/function calls instead of method calls. I add a patch to get "this." to work with function calls so sync to the latest git before trying the example otherwise the first method call will be a syntax error. Using "this." works around the problem, but that is not acceptable for general user code.
I may look at this so ask before taking this report.
I have pushed a fix for this issue.