GB: Adding or removing mapping displays browser console errors

Clicking on Gradebook -> Settings, I modified all settings without errors until I got to the Grading Schema.

I removed the F and received the following console error:

Chart.min.js?version=:10 Failed to create chart: can't acquire context from the given item
construct @ Chart.min.js?version=:10

When trying to add the F back to the chart, I was able to add the "F", but when I clicked in the textbox to enter the score, another error displayed and I could not enter the 0 until I clicked in the textbox a second time.

Chart.min.js?version=:10 Failed to create chart: can't acquire context from the given item
construct @ Chart.min.js?version=:10

When clicking to Add Mapping, then Remove beside the empty row, both of the above errors display. Am attaching the files with errors.

I did not see any errors in the server logs.