feat: ensure bot invites work correctly

crates/core/result/src/lib.rs

@@ -88,6 +88,7 @@ pub enum ErrorType {
     TooManyRoles {
         max: usize,
     },
+    AlreadyInServer,
 
     // ? Bot related errors
     ReachedMaximumBots,

crates/core/result/src/rocket.rs

@@ -43,6 +43,7 @@ impl<'r> Responder<'r, 'static> for Error {
             ErrorType::UnknownServer => Status::NotFound,
             ErrorType::InvalidRole => Status::NotFound,
             ErrorType::Banned => Status::Forbidden,
+            ErrorType::AlreadyInServer => Status::Conflict,
 
             ErrorType::TooManyServers { .. } => Status::BadRequest,
             ErrorType::TooManyEmoji { .. } => Status::BadRequest,