Fix errors not having a message property (#45)

* Fix errors not having a message property

README.md

@@ -121,8 +121,8 @@ Wrapped function can throw `NotRetryableError` if retrying need to be stopped ev
 ```typescript
 import { NotRetryableError } from 'ts-retry-promise';
 
-retry(async () => throw new NotRetryableError("This error"))
-    .catch(err => console.log(err.lastError), { retries: 'INFINITELY' });
+retry(async () => { throw new NotRetryableError("This error") }, { retries: 'INFINITELY' })
+    .catch(err => console.log(err.lastError.message));  // will print "This error"
 ```
 
 ## Samples ##

src/retry-promise.ts

@@ -141,7 +141,7 @@ export class RetryError extends Error {
 
 // tslint:disable-next-line:max-classes-per-file
 class BaseError {
-    constructor (...args: unknown[]) {
+    constructor (public message?: string, ...args: unknown[]) {
         Error.apply(this, args as any);
     }
 }

test/notretryable.error.test.ts

@@ -11,6 +11,20 @@ describe("NotRetryableError Error", () => {
     expect(failer.calls).to.eq(1);
   });
 
+  it("should have RetryError in lastError", async () => {
+    const error = new NotRetryableError("stop retrying");
+
+    const result = retry(async () => {throw error});
+
+    expect(result).to.be.eventually.rejected.with.property("lastError").eq(error);
+  });
+
+  it("RetryError should have message", async () => {
+      const error = new NotRetryableError("stop retrying");
+
+      expect(error.message).to.eq("stop retrying");
+  });
+
 });
 
 class Failer {

test/retry-promise.demo.test.ts

@@ -1,5 +1,5 @@
 import {expect} from "./index";
-import {customizeRetry, defaultRetryConfig, retry, retryDecorator, wait} from "../src/retry-promise";
+import {customizeRetry, defaultRetryConfig, NotRetryableError, retry, retryDecorator, wait} from "../src/retry-promise";
 
 describe("Retry Promise Demo", () => {
 
@@ -97,6 +97,17 @@ describe("Retry Promise Demo", () => {
         expect(profile.name).to.eq("Mr 123");
     })
 
+    it("NotRetryableError demo", async () => {
+
+        const result = retry(
+            async () => { throw new NotRetryableError("This error"); },
+            { retries: 'INFINITELY' })
+            // tslint:disable-next-line:no-console
+            .catch(err => console.log(err.lastError.message));  // will print "This error"
+
+        await result;
+    })
+
 });
 
 const browser = {