null check for markers

src/vs/workbench/api/electron-browser/mainThreadDiagnostics.ts

@@ -29,10 +29,12 @@ export class MainThreadDiagnostics implements MainThreadDiagnosticsShape {
 	$changeMany(owner: string, entries: [UriComponents, IMarkerData[]][]): void {
 		for (let entry of entries) {
 			let [uri, markers] = entry;
-			for (const marker of markers) {
-				if (marker.relatedInformation) {
-					for (const relatedInformation of marker.relatedInformation) {
-						relatedInformation.resource = URI.revive(relatedInformation.resource);
+			if (markers) {
+				for (const marker of markers) {
+					if (marker.relatedInformation) {
+						for (const relatedInformation of marker.relatedInformation) {
+							relatedInformation.resource = URI.revive(relatedInformation.resource);
+						}
 					}
 				}
 			}