Problem description: It is not possible to set override Missing data to "Last known" in Overrides tab in Graph widget configuration form: the following error is returned:
Steps to reproduce:
- Open any existing Graph widget configuration
- Switch to Overrides tab
- Set any of the configured metrics in Overrides field
- Add the following override to it: Missing data = Last known
- Attempt to save widget configuration.
Result: widget configuration is not saved. The above error is observed.
Expected: widget configuration should be successfully saved.