code: function getErrorStack (ex) {
    let ret = ex.stack || ex.toString()
    if (ex.cause && typeof ex.cause === 'function') {
      const cex = ex.cause()
      if (cex) ret += '\nCaused by: ' + getErrorStack(cex)
    }
    return ret
  }
docs: ────────────────────────────────  Private  ────────────────────────────────── 
  Gets the Error Stack as a String.
  
  @param  {any} ex Error Object
  
  @return {String}