The span of the invalid code in the file. Could be undefined if the diagnostic is system-level (and not file-specific), like e.g. an error about invalid TS options.

Source file name. Could be undefined if the diagnostic is system-level (and not file-specific), like e.g. an error about invalid TS options.

TypeScript error code.

Error category from the TypeScript compiler.

The error or warning message describing the diagnostic.