Fix wrong variable name

Author: bradjones1

src/transports/WebSocketTransport.ts

@@ -33,7 +33,7 @@ class WebSocketTransport extends Transport {
       if (err) {
         const jsonError = err instanceof JSONRPCError
           ? err
-          : new JSONRPCError(e.message, ERR_UNKNOWN, err);
+          : new JSONRPCError(err.message, ERR_UNKNOWN, err);
         this.transportRequestManager.settlePendingRequest(notifications, jsonError);
         this.transportRequestManager.settlePendingRequest(getBatchRequests(data), jsonError);
         prom = Promise.reject(jsonError);