return the error when refresh fails, not the token (#49)

* return the error when refresh fails, not the token

* changelog

aad/jwt.go

@@ -178,7 +178,7 @@ func (c *TokenProviderConfiguration) NewServicePrincipalToken() (*adal.ServicePr
 			return nil, fmt.Errorf("failed to get oauth token from certificate auth: %v", err)
 		}
 		if err := spToken.Refresh(); err != nil {
-			return nil, fmt.Errorf("failed to refersh token: %v", spToken)
+			return nil, fmt.Errorf("failed to refresh token: %v", err)
 		}
 		return spToken, nil
 	}

changelog.md

@@ -1,6 +1,7 @@
 # Change Log
 
 ## `head`
+- fix refresh error to return the underlying http error instead of the token
 
 ## `v2.1.1`
 - bump amqp to v0.12.1