Make GraphError real Error (#335)

Co-authored-by: nikithauc <nikithauc@gmail.com>

Author: OlivierCuyp

spec/core/GraphErrorHandler.ts

@@ -97,9 +97,9 @@ describe("GraphErrorHandler.ts", () => {
 
 		it("Should construct some default error", async () => {
 			const gError = await GraphErrorHandler.getError();
+			assert.equal(gError.message, "");
 			assert.equal(gError.statusCode, -1);
 			assert.equal(gError.code, null);
-			assert.equal(gError.message, null);
 			assert.equal(gError.body, null);
 			assert.equal(gError.requestId, null);
 		});

src/GraphError.ts

@@ -17,7 +17,7 @@
  * Some fields are renamed ie, "request-id" => requestId so you can use dot notation
  */
 
-export class GraphError {
+export class GraphError extends Error {
 	/**
 	 * @public
 	 * A member holding status code of the error
@@ -30,12 +30,6 @@ export class GraphError {
 	 */
 	public code: string | null;
 
-	/**
-	 * @public
-	 * A member holding error message
-	 */
-	public message: string | null;
-
 	/**
 	 * @public
 	 * A member holding request-id i.e identifier of the request
@@ -61,12 +55,13 @@ export class GraphError {
 	 * @param {number} [statusCode = -1] - The status code of the error
 	 * @returns An instance of GraphError
 	 */
-	public constructor(statusCode: number = -1) {
+	public constructor(statusCode: number = -1, message?: string, baseError?: Error) {
+		super(message || (baseError && baseError.message));
 		this.statusCode = statusCode;
 		this.code = null;
-		this.message = null;
 		this.requestId = null;
 		this.date = new Date();
 		this.body = null;
+		this.stack = baseError ? baseError.stack : this.stack;
 	}
 }

src/GraphErrorHandler.ts

@@ -27,12 +27,11 @@ export class GraphErrorHandler {
 	 * @returns The GraphError instance
 	 */
 	private static constructError(error: Error, statusCode?: number): GraphError {
-		const gError = new GraphError(statusCode);
+		const gError = new GraphError(statusCode, "", error);
 		if (error.name !== undefined) {
 			gError.code = error.name;
 		}
 		gError.body = error.toString();
-		gError.message = error.message;
 		gError.date = new Date();
 		return gError;
 	}
@@ -60,9 +59,8 @@ export class GraphErrorHandler {
 	 */
 	private static constructErrorFromResponse(error: any, statusCode: number): GraphError {
 		error = error.error;
-		const gError = new GraphError(statusCode);
+		const gError = new GraphError(statusCode, error.message);
 		gError.code = error.code;
-		gError.message = error.message;
 		if (error.innerError !== undefined) {
 			gError.requestId = error.innerError["request-id"];
 			gError.date = new Date(error.innerError.date);