An error or warning OpenTofu reported in its machine-readable UI. The fields
follow https://opentofu.org/docs/cli/commands/validate/#json.
- Severity of the diagnostic. A state error holds only ERROR diagnostics.
- summaryA short description of the problem.
- detailMore detail about the problem, possibly over several paragraphs. Null when OpenTofu reported none.
- The part of the configuration the diagnostic points at. Null when OpenTofu reported none.
- An excerpt of the configuration around `range`. Null when OpenTofu reported none.