extensions/typescript-language-features/src/typeScriptServiceClientHost.ts/TypeScriptServiceClientHost/getDiagnosticSeverity
class TypeScriptServiceClientHost:	private getDiagnosticSeverity(diagnostic: Proto.Diagnostic): vscode.DiagnosticSeverity {
		if (this.reportStyleCheckAsWarnings
			&& this.isStyleCheckDiagnostic(diagnostic.code)
			&& diagnostic.category === PConst.DiagnosticCategory.error
		) {
			return vscode.DiagnosticSeverity.Warning;
		}

		switch (diagnostic.category) {
			case PConst.DiagnosticCategory.error:
				return vscode.DiagnosticSeverity.Error;

			case PConst.DiagnosticCategory.warning:
				return vscode.DiagnosticSeverity.Warning;

			case PConst.DiagnosticCategory.suggestion:
				return vscode.DiagnosticSeverity.Hint;

			default:
				return vscode.DiagnosticSeverity.Error;
		}
	}