fix(client/streamableHttp): retry sendMessage on 401

After receiving a 401, attempt to `auth`. Whether the authorization
works immediately or causes a redirect, retry sending the message.

Author: chrisdickinson

src/client/streamableHttp.ts

@@ -401,10 +401,8 @@ export class StreamableHTTPClientTransport implements Transport {
 
       if (!response.ok) {
         if (response.status === 401 && this._authProvider) {
-          const result = await auth(this._authProvider, { serverUrl: this._url });
-          if (result !== "AUTHORIZED") {
-            throw new UnauthorizedError();
-          }
+          // Whether this is REDIRECT or AUTHORIZED, retry sending the message.
+          await auth(this._authProvider, { serverUrl: this._url });
 
           // Purposely _not_ awaited, so we don't call onerror twice
           return this.send(message);