hom_server in login response is optional

Since it is depreated it will also be removed in the future.
Fixes #7

lib/structs/responses/login.cpp

@@ -12,7 +12,9 @@ from_json(const json &obj, Login &response)
         response.user_id = obj.at("user_id").get<User>();
 
         response.access_token = obj.at("access_token").get<std::string>();
-        response.home_server  = obj.at("home_server").get<std::string>();
+
+        if (obj.count("home_server") != 0)
+                response.home_server = obj.at("home_server").get<std::string>();
 
         if (obj.count("device_id") != 0)
                 response.device_id = obj.at("device_id").get<std::string>();

tests/responses.cpp

@@ -524,6 +524,16 @@ TEST(Responses, Login)
         EXPECT_EQ(login2.access_token, "abc123");
         EXPECT_EQ(login2.home_server, "matrix.org");
         EXPECT_EQ(login2.device_id, "");
+
+        json data3   = R"({
+          "user_id": "@cheeky_monkey:matrix.org",
+          "access_token": "abc123"
+        })"_json;
+        Login login3 = data3;
+        EXPECT_EQ(login3.user_id.to_string(), "@cheeky_monkey:matrix.org");
+        EXPECT_EQ(login3.access_token, "abc123");
+        EXPECT_EQ(login3.home_server, "");
+        EXPECT_EQ(login3.device_id, "");
 }
 
 TEST(Responses, Messages)