Fix some type issues (#66)

* Fix some type errors

* More fixup

* fixup! More fixup

* Remove needlessly complicated XOR type

* fixup! Remove needlessly complicated XOR type

Author: rekmarks

src/index.d.ts

@@ -1,63 +1,77 @@
 
 import { IEthereumRpcError } from 'eth-rpc-errors/@types'
 
-/** A String specifying the version of the JSON-RPC protocol. MUST be exactly "2.0". */
+/**
+ * A String specifying the version of the JSON-RPC protocol.
+ * MUST be exactly "2.0".
+ */
 export type JsonRpcVersion = "2.0";
 
 /** Method names that begin with the word rpc followed by a period character
  * (U+002E or ASCII 46) are reserved for rpc-internal methods and extensions
- *  and MUST NOT be used for anything else. */
+ * and MUST NOT be used for anything else.
+ */
 export type JsonRpcReservedMethod = string;
 
-/** An identifier established by the Client that MUST contain a String, Number,
- *  or NULL value if included. If it is not included it is assumed to be a
- *  notification. The value SHOULD normally not be Null and Numbers SHOULD
- *  NOT contain fractional parts [2] */
+/**
+ * An identifier established by the Client that MUST contain a String, Number,
+ * or NULL value if included. If it is not included it is assumed to be a
+ * notification. The value SHOULD normally not be Null and Numbers SHOULD
+ * NOT contain fractional parts.
+ */
 export type JsonRpcId = number | string | void;
 
-interface JsonRpcError<T> extends IEthereumRpcError<T> {}
+export interface JsonRpcError<T> extends IEthereumRpcError<T> {}
 
-interface JsonRpcRequest<T> {
+export interface JsonRpcRequest<T> {
   jsonrpc: JsonRpcVersion;
   method: string;
   id: JsonRpcId;
   params?: T;
 }
 
-interface JsonRpcNotification<T> extends JsonRpcResponse<T> {
+export interface JsonRpcNotification<T> {
   jsonrpc: JsonRpcVersion;
+  method: string,
   params?: T;
 }
 
-interface JsonRpcResponse<T> {
-  result?: any;
-  error?: JsonRpcError<any>;
-  jsonrpc: JsonRpcVersion;
-  id: JsonRpcId;
+interface JsonRpcResponseBase {
+  jsonrpc: JsonRpcVersion,
+  id: JsonRpcId,
 }
 
-interface JsonRpcSuccess<T> extends JsonRpcResponse<T> {
-    result: any;
+export interface JsonRpcSuccess<T> extends JsonRpcResponseBase {
+  result: T;
 }
 
-interface JsonRpcFailure<T> extends JsonRpcResponse<T> {
-    error: JsonRpcError<T>;
+export interface JsonRpcFailure<T> extends JsonRpcResponseBase {
+  error: JsonRpcError<T>;
 }
 
-type JsonRpcEngineEndCallback = (error?: JsonRpcError<any>) => void;
-type JsonRpcEngineNextCallback = (returnFlightCallback?: (done: () => void) => void) => void;
+export type JsonRpcResponse<T> = JsonRpcSuccess<T> | JsonRpcFailure<T>
 
-interface JsonRpcMiddleware {
+export type JsonRpcEngineEndCallback = (error?: JsonRpcError<unknown>) => void;
+export type JsonRpcEngineNextCallback = (
+  returnFlightCallback?: (done: () => void) => void,
+) => void;
+
+export interface JsonRpcMiddleware {
   (
-    req: JsonRpcRequest<any>,
-    res: JsonRpcResponse<any>,
+    req: JsonRpcRequest<unknown>,
+    res: JsonRpcResponse<unknown>,
     next: JsonRpcEngineNextCallback,
     end: JsonRpcEngineEndCallback,
   ) : void;
 }
 
-interface JsonRpcEngine {
+export interface JsonRpcEngine {
   push: (middleware: JsonRpcMiddleware) => void;
-  handle: (req: JsonRpcRequest<any>, callback: (error: JsonRpcError<any>, res: JsonRpcResponse<any>) => void) => void;
+  handle: (
+    req: JsonRpcRequest<unknown>,
+    callback: (
+      error: JsonRpcError<unknown>,
+      res: JsonRpcResponse<unknown>,
+    ) => void,
+  ) => void;
 }
-