[I] DiagnosticDefinition
Declare a diagnostic that can be reported by the library.
Example
unterminated: {  severity: "error",  description: "Unterminated token.",  url: "https://example.com/docs/diags/unterminated",  messages: {    default: paramMessage`Unterminated ${"token"}.`,  },},Type Parameters
| Type Parameter | 
|---|
| MextendsDiagnosticMessages |