function unwrapArray(arg, defaultValue) {
  arg = Array.isArray(arg) ? /* istanbul ignore next (preact) */ arg[0] : arg
  if (!arg && defaultValue) {
    return defaultValue
  } else {
    return arg
  }
}
Takes an argument and if it's an array, returns the first item in the array
otherwise returns the argument
@param {*} arg the maybe-array
@param {*} defaultValue the value if arg is falsey not defined
@return {*} the arg or it's first item