if (!nativeThis) return JS_FALSE;
InstallGetLastError(JSContext *cx, JSObject *obj, uintN argc, jsval *argv, jsval *rval){  nsInstall *nativeThis =    (nsInstall*)JS_GetInstancePrivate(cx, obj, &InstallClass, argv);  if (!nativeThis)    return JS_FALSE;  PRInt32 nativeRet;  *rval = INT_TO_JSVAL(nsInstall::UNEXPECTED_ERROR);  // If there's no private data, this must be the prototype, so ignore  if (nsnull == nativeThis) {    return JS_TRUE;  }  //  public int GetLastError (void);  if(NS_OK == nativeThis->GetLastError(&nativeRet)) {    *rval = INT_TO_JSVAL(nativeRet);  }  return JS_TRUE;}