Puppet::FileSystem.chmod doesn't validate its arguments like other FS methods

Puppet::FileSystem methods generally assert that they are passed either a String or Pathname and raise ArgumentError if that isn't the case. For example:

irb(main):009:0> Puppet::FileSystem.mkpath(nil)

...

ArgumentError (FileSystem implementation expected Pathname, got: 'NilClass')

However, Puppet::FileSystem.chmod raises an unhelpful TypeError trying to convert nil to a String:

irb(main):007:0> Puppet::FileSystem.chmod(0644, nil)

...

TypeError (no implicit conversion of nil into String)

The chmod method should raise ArgumentError like the other methods