Thanks for getting in touch!
After some investigation I found this to be an issue with our crosshair's interpolation code that positions the crosshair between two datapoints.
A work around solution to prevent this crash would be to turn off point interpolation on your crosshair by using the following code:
chart.crosshair.interpolatePoints = NO;
I have added this issue to our backlog and a member of our team will update this forum post when the fix for this issue has been released.
Let me know if you have any questions.