Missing Error declaration in some pallets

[h4x3rotab]

Now if we check rpc.state.getMetadata, there are a lot of pallets without error declarations populated in metadata it returns. We have checked Phala PoC3 and Polkadot (at the latest block, and block 1000). All of them have this problem.

For example, if you search "Indices" pallet, and find the errors field in its entry, it shows:

          errors: [],
          index: 4

This will cause errors in polkadotjs and subxt whenever they decode a block with the errors from these bad pallets.

However, not all the pallets have this problem. We checked around the definition of the bad pallets and good pallets, and found all the bad pallets forgot to declare the error inside decl_module!. So we suspect this is the root cause. Now we cannot dedicate some time for further testing. So I just created this issue and leave it as a record.

Good example:

substrate/frame/recovery/src/lib.rs

Lines 325 to 327 in 88243c1

	decl_module! {
	pub struct Module<T: Config> for enum Call where origin: T::Origin {
	type Error = Error<T>;

Bad example:

substrate/frame/indices/src/lib.rs

Lines 105 to 111 in 88243c1

	decl_module! {
	pub struct Module<T: Config> for enum Call where origin: T::Origin, system = frame_system {
	/// The deposit needed for reserving an index.
	const Deposit: BalanceOf<T> = T::Deposit::get();
	fn deposit_event() = default;

A full list of the good pallets (by grep type Error = Error<T> in the frame directory):

substrate/frame/assets/src/lib.rs:
substrate/frame/atomic-swap/src/lib.rs:
substrate/frame/authorship/src/lib.rs:
substrate/frame/balances/src/lib.rs:
substrate/frame/collective/src/lib.rs:
substrate/frame/contracts/src/lib.rs:
substrate/frame/democracy/src/lib.rs:
substrate/frame/elections/src/lib.rs:
substrate/frame/elections-phragmen/src/lib.rs:
substrate/frame/evm/src/lib.rs:
substrate/frame/grandpa/src/lib.rs:
substrate/frame/identity/src/lib.rs:
substrate/frame/im-online/src/lib.rs:
substrate/frame/multisig/src/lib.rs:
substrate/frame/nicks/src/lib.rs:
substrate/frame/node-authorization/src/lib.rs:
substrate/frame/proxy/src/lib.rs:
substrate/frame/recovery/src/lib.rs:
substrate/frame/scheduler/src/lib.rs:
substrate/frame/scored-pool/src/lib.rs:
substrate/frame/session/src/lib.rs:
substrate/frame/society/src/lib.rs:
substrate/frame/staking/src/lib.rs:
substrate/frame/sudo/src/lib.rs:
substrate/frame/support/src/metadata.rs:
substrate/frame/system/src/lib.rs:
substrate/frame/treasury/src/lib.rs:
substrate/frame/vesting/src/lib.rs:

[xlc]

Related #6418

[shawntabrizi]

This would be a good first issue for any people who want to hunt down all the missing errors.

[h4x3rotab]

Would appreciate if we can get a quick fix because all the miners on our network were halted :(

[shawntabrizi]

@h4x3rotab can you elaborate on how this has broke your miners?

You should be able to handle no error metadata, as it is clearly not required, and basically you should not expect it from all Substrate teams.

[jasl]

@h4x3rotab can you elaborate on how this has broke your miners?

You should be able to handle no error metadata, as it is clearly not required, and basically you should not expect it from all Substrate teams.

It breaks SubXT, I attached a PR for them to workaround this

[KiChjang]

It seems like that there's quite a lot of pallets nowadays that don't use the decl_module macro to implement dispatch logic anymore, and instead uses the #[pallet] macro. Pallets using the new attribute macro don't seem to need the type Error = Error<T> line anymore; instead, #[pallet::error] looks to be enough. Am I missing anything here?

[shawntabrizi]

@KiChjang yes, that is accurate. Thew new macros solve this issue. But old pallets could be patched up in the meantime.

Or you can spend your time to migrate the old pallets into the new macro.