Set a default redirect_uri if none is provided

src/registration.rs

@@ -18,9 +18,14 @@ pub struct Registration {
 struct OAuth {
     client_id: String,
     client_secret: String,
+    #[serde(default = "default_redirect_uri")]
     redirect_uri: String,
 }
 
+fn default_redirect_uri() -> String {
+    "urn:ietf:wg:oauth:2.0:oob".to_string()
+}
+
 #[derive(Deserialize)]
 struct AccessToken {
     access_token: String,