fix(xen-api/_call): ensure args always defined

Otherwise it might cause JSON-RPC issue on some XAPI versions (missing `params` field) or problems when augmenting errors with `call.params` (*TypeError: Cannot read properties of undefined (reading '0')*).

packages/xen-api/src/index.js

@@ -728,7 +728,7 @@ export class Xapi extends EventEmitter {
   // Private
   // ===========================================================================
 
-  async _call(method, args, timeout = this._callTimeout(method, args)) {
+  async _call(method, args = [], timeout = this._callTimeout(method, args)) {
     const startTime = Date.now()
     try {
       const result = await pTimeout.call(this._addSyncStackTrace(this._transport(method, args)), timeout)