in package/src/languageFeatures.ts [337:350]
function toDiagnostics(resource: monaco.Uri, diag: ls.Diagnostic): monaco.editor.IMarkerData {
let code = typeof diag.code === 'number' ? String(diag.code) : <string>diag.code;
return {
severity: toSeverity(diag.severity),
startLineNumber: diag.range.start.line + 1,
startColumn: diag.range.start.character + 1,
endLineNumber: diag.range.end.line + 1,
endColumn: diag.range.end.character + 1,
message: diag.message,
code: code,
source: diag.source,
};
}