`Buffer` is not a browser method

[sartaj-devoted]

PubNub client has been failing for us since we upgraded to the latest Webpack, which no longer polyfills nodejs methods.

The issue here is that this library uses a non standard global Buffer method. There may be a case where this is failing for others who have upgraded to the latest compilers too.

Some thoughts:

1. Convert to using browser standards for buffers.
2. If that is not in the timelines, perhaps make the error more graceful, with the library explicitly checking for if Buffer exists. I wouldn't be surprised if other users of PubNub are not aware their client started failing due to a webpack upgrade.

As an aside, are there docs on where/how to handle errors like this? We weren't aware of the issue for months as nothing obvious was erroring within the addListener({message method, and logVerbosity:true did not surface any errors.

[sartaj-devoted]

As a solution to at least fix the base64=>buffer problem, I was able to replace `Buffer.from(b64str, 'base64') with the following:

if (!window.Buffer) {
  window.Buffer = {
    from: (base64_string: string, encoding: BufferEncoding): Buffer => {
      if (encoding !== 'base64') {
        throw new Error('Buffer polyfill only supports base64 encoding');
      }
      return Uint8Array.from(window.atob(base64_string), c =>
        c.charCodeAt(0),
      ) as any;
    },
  } as any;
}

I think this project could find other uses of Buffer, and replace them with built in browser methods.