Resolving review comments

Author: muthurathinam-m

README.md

@@ -59,7 +59,7 @@ supported authentication portals:
 
 ### 2. Authenticate for the Microsoft Graph service
 
-The Microsoft Graph JavaScript Client Library has an adapter implementation ([MSALAuthenticationProvider](src/MSALAuthenticationProvider.ts)) for [MSAL](https://github.com/AzureAD/microsoft-authentication-library-for-js/tree/dev/lib/msal-core) (Microsoft Authentication Library) which takes care of getting the `accessToken`. MSAL library does not ship with this library, user have to include it externally (For including MSAL, refer [this](https://github.com/AzureAD/microsoft-authentication-library-for-js/tree/dev/lib/msal-core#installation)).
+The Microsoft Graph JavaScript Client Library has an adapter implementation ([MSALAuthenticationProvider](src/MSALAuthenticationProvider.ts)) for [MSAL](https://github.com/AzureAD/microsoft-authentication-library-for-js/tree/dev/lib/msal-core) (Microsoft Authentication Library) which takes care of getting the `accessToken`. MSAL library does not ship with this library, user has to include it externally (For including MSAL, refer [this](https://github.com/AzureAD/microsoft-authentication-library-for-js/tree/dev/lib/msal-core#installation)).
 
 > **Note:** MSAL is supported only for frontend applications, for server-side authentication you have to implement your own AuthenticationProvider. Refer implementing [Custom Authentication Provider](./docs/CustomAuthenticationProvider.md).
 

docs/CreatingClientInstance.md

@@ -8,7 +8,7 @@ In order to instantiate a Client object, one has to pass in the `authProvider` o
 
 ### Option A. Default Middleware chain
 
-Pass an instance of a class which implementing [AuthenticationProvider](../src/IAuthenticationProvider.ts) interface as `authProvider` in [ClientOptions](../src/IClientOptions.ts), which will instantiate the Client with default set of middleware chain.
+Pass an instance of a class which implements [AuthenticationProvider](../src/IAuthenticationProvider.ts) interface as `authProvider` in [ClientOptions](../src/IClientOptions.ts), which will instantiate the Client with default set of middleware chain.
 
 Library is shipped with one such authentication provider named [MSALAuthenticationProvider](../src/MSALAuthenticationProvider.ts). This MSALAuthenticationProvider depends on an authentication library [msal.js](https://github.com/AzureAD/microsoft-authentication-library-for-js) which is not shipped along with the library, one has to externally include msal.js to use MSALAuthenticationProvider.
 
@@ -49,7 +49,7 @@ Refer, [custom middleware chain](./CustomMiddlewareChain.md) for more detailed i
 
 ## 2. Create With Options
 
-Pass an [authProvider function](../src/IAuthProvider.ts) in [Options](../src/IOptions.ts) while initializing the Client. In this case, user have to provide his own implementation for getting and refreshing accessToken. A callback will be passed into this authProvider function, accessToken or error needs to be passed in to that callback.
+Pass an [authProvider function](../src/IAuthProvider.ts) in [Options](../src/IOptions.ts) while initializing the Client. In this case, user has to provide his own implementation for getting and refreshing accessToken. A callback will be passed into this authProvider function, accessToken or error needs to be passed in to that callback.
 
 ```typescript
 // Some callback function

lib/graph-js-sdk-core.js

@@ -25,6 +25,19 @@ describe("Client.ts", function () {
         const dummyAuthProvider = new DummyAuthenticationProvider(),
             customHTTPHandler = new CustomHTTPHandler();
 
+        it("Should throw an error in case if both auth provider and custom middleware is passed", () => {
+            try {
+                const options: ClientOptions = {
+                    authProvider: dummyAuthProvider,
+                    middleware: customHTTPHandler
+                };
+                const client: Client = Client.initWithMiddleware(options);
+                throw new Error("Something wrong with the ambiguity check");
+            } catch(error) {
+                assert.equal(error.name, "AmbiguityInInitialization");
+            }
+        });
+
         it("Should return client instance for an authentication provider", () => {
             let options: ClientOptions = {
                 authProvider: dummyAuthProvider

lib/graph-js-sdk-web.js

@@ -53,7 +53,12 @@ export class Client {
             self.config[key] = clientOptions[key];
         }
         let httpClient: HTTPClient;
-        if (clientOptions.authProvider !== undefined) {
+        if(clientOptions.authProvider !== undefined && clientOptions.middleware !== undefined) {
+            const error = new Error();
+            error.name = "AmbiguityInInitialization";
+            error.message = "Unable to Create Client, Please provide either authentication provider for default middleware chain or custom middleware chain not both";
+            throw error;
+        } else if (clientOptions.authProvider !== undefined) {
             httpClient = HTTPClientFactory.createWithAuthenticationProvider(clientOptions.authProvider);
         } else if (clientOptions.middleware !== undefined) {
             httpClient = new HTTPClient(clientOptions.middleware);
@@ -93,7 +98,11 @@ export class Client {
      * @returns The Client instance 
      */
     public static initWithMiddleware(options: ClientOptions): Client {
-        return new Client(options);
+        try {
+            return new Client(options);
+        } catch (error) {
+            throw error;
+        }
     }
 
     /**