Fix Invalid type assignment in SafeEventEmitterProvider

[kanthesha]

The Record<never, never> type assigned to response of convertEip1193RequestToJsonRpcRequest does not belong here (link to the code), no possible return value is represented by that type.

We need to fix/simplify the type assignment.

[kanthesha]

export function convertEip1193RequestToJsonRpcRequest<
  Params extends JsonRpcParams,
>(
  eip1193Request: Eip1193Request<Params>,
): JsonRpcRequest<Params | Record<never, never>> {
  const { id = uuidV4(), jsonrpc = '2.0', method, params } = eip1193Request;
  return params
    ? {
        id,
        jsonrpc,
        method,
        params,
      }
    : {
        id,
        jsonrpc,
        method,
      };
}

In the above function, the type of params in JsonRpcRequest is (((Record<string, Json> | Json[]) & ExactOptionalGuard) & JsonRpcParams) | undefined> and type of JsonRpcParams is Json[] | Record<string, Json>.
So we need Record<never, never> to widen the type so that it matches with the type of params in JsonRpcRequest.

We can try replacing Params extends JsonRpcParams with Params extends JsonRpcRequest['params']. But this way, we get type error in the : JsonRpcRequest<Params>, because JsonRpcRequest has type JsonRpcRequest<Params extends JsonRpcParams = JsonRpcParams>.

I think, if we have to fix this, we need to align the JsonRpcRequest generic type with the type of params in JsonRpcRequest.

Additional Reference:
Actual JsonRpcRequest type

export type JsonRpcRequest<Params extends JsonRpcParams = JsonRpcParams> = InferWithParams<typeof JsonRpcRequestStruct, Params>;

which will expand to

type JsonRpcRequest<Params extends JsonRpcParams = JsonRpcParams> = {
    params?: (Record<string, Json> | Json[]) & ExactOptionalGuard;
    id: string | number | null;
    method: string;
    jsonrpc: "2.0";
}

cc: @Gudahtt

[Gudahtt]

So we need Record<never, never> to widen the type so that it matches with the type of params in JsonRpcRequest.

Hmm, I'm not really following how those difference in types is resolved by this addition. How does adding Record<never, never> widen the type? It's unclear to me which piece of the left type requires that.

[kanthesha]

It is something to do with ExactOptionalGuard! tested by remove that in JsonRpcRequest, then it works fine without Record<never, never> in response (: JsonRpcRequest<Params>).

[mcmire]

Just seeing this issue now. I think this was my attempt to get something working with convertEip1193RequestToJsonRpcRequest without fully understanding the intricacies of the JsonRpcRequest type. In using Record<never, never> I was trying to represent the possibility that params on the given eip1193Request could be ignored and therefore not set on the JsonRpcRequest being built, but I agree that it's not the right way to solve this problem. I'll have to think more about what a good solution here would be.