SAK-40432 Modify GradebookNG to handle negative scores (#5877) * SAK-40432 Support negative grades in GradebookNG
Although GradebookNG won't let you enter a negative grade, they can find their way in via external tools (like Samigo) in the form of grade overrides. Gradebook Classic shows these scores, whereas GradebookNG would throw a JS exception. Modify GradebookNG to handle this case.
* SAK-40432 highlight when external tool has provided a negative score in the GradebookNG table
(cherry picked from commit 2598b5494cc9a81c43433079e6b1b65485c410c9)