How to publish on Pubnub with node mcu?
The pubchannel and subchannel can be defined as any values in char variable.

Here is the right code:-

const char * pubkey = "publisher key from your account";
const char * subkey = "subscriber key from your account";

const char * pubchannel = "demo_keyset";
const char * subchannel = "demo_keyset";


Then the error disappeared