The information associated with this error, in structured form.
The first node is typically an ErrorSummary giving a short description of the problem, suitable for an index of errors, a log, etc.
Subsequent nodes should give information specific to this error. Typically these will be ErrorDescriptions or ErrorHints, but they could be other objects also. For instance, an error relating to a timer could include a stack trace of when the timer was scheduled using the DiagnosticsStackTrace class.
final List<DiagnosticsNode> diagnostics