Return error info for access token requests

lib/threads/api/oauth2/client.rb

@@ -2,7 +2,7 @@ module Threads
   module API
     module OAuth2
       class Client
-        ShortLivedResponse = Struct.new(:access_token, :user_id)
+        ShortLivedResponse = Struct.new(:access_token, :user_id, :error_type, :error_message, :code)
         LongLivedResponse = Struct.new(:access_token, :token_type, :expires_in)
 
         def initialize(client_id:, client_secret:)
@@ -19,7 +19,7 @@ def access_token(code:, redirect_uri:)
             redirect_uri: redirect_uri
           })
 
-          ShortLivedResponse.new(*response.body.values_at("access_token", "user_id"))
+          ShortLivedResponse.new(*response.body.values_at("access_token", "user_id", "error_type", "error_message", "code"))
         end
 
         def exchange_access_token(access_token)

spec/threads/api/oauth2/client_spec.rb

@@ -24,6 +24,19 @@
       expect(response.access_token).to eq("ACCESS_TOKEN")
       expect(response.user_id).to eq(1234567890)
     end
+
+    context "when an error occurs" do
+      let!(:request) do
+        stub_request(:post, "https://graph.threads.net/oauth/access_token")
+          .to_return(body: {error_type: "invalid_request", error_message: "Invalid redirect URI", code: 400}.to_json, headers: {"Content-Type" => "application/json"})
+      end
+
+      it "returns an error response" do
+        expect(response.error_type).to eq("invalid_request")
+        expect(response.error_message).to eq("Invalid redirect URI")
+        expect(response.code).to eq(400)
+      end
+    end
   end
 
   describe "#exchange_access_token" do