After removing an annotation the chart throws errors

[morganfree]

Actual behaviour

After chart.removeAnnotation() the chart throws the error:
Uncaught TypeError: Array.prototype.forEach called on null or undefined

Live demo with steps to reproduce

http://jsfiddle.net/5L7ta5fb/

1. Run the fiddle
2. Open the browser console

Product version

All products 6+

An annotation is not destroyed correctly - chart.labelsCollectors still runs the removed annotation's label collector - the collector refers to removed props.