Auto-correct for Style/MultilineArrayBraceLayout produces invalid code

[jspanjers]

When you run auto-correct for Style/MultilineArrayBraceLayout on code with arrays containing trailing comma's, the output code contains errors.

---

Steps to reproduce the problem

$ cat > test.rb << EOF
# encoding: utf-8
# frozen_string_literal: true
class Test
  def test
    [a, # a
     b, # b
    ]
  end
end
EOF

$ bundle exec rubocop test.rb
Inspecting 1 file
C

Offenses:

test.rb:5:5: C: Closing array brace must be on the same line as the last array element when opening brace is on the same line as the first array element.
    [a, # a ...
    ^^^^^^^

1 file inspected, 1 offense detected


$ bundle exec rubocop --auto-correct test.rb
Inspecting 1 file
E

Offenses:

test.rb:5:5: C: [Corrected] Closing array brace must be on the same line as the last array element when opening brace is on the same line as the first array element.
    [a, # a ...
    ^^^^^^^
test.rb:6:8: E: unexpected token tCOMMA
(Using Ruby 1.9 parser; configure using TargetRubyVersion parameter, under AllCops)
     b], # b
       ^

1 file inspected, 2 offenses detected, 1 offense corrected


$ cat test.rb
# encoding: utf-8
# frozen_string_literal: true
class Test
  def test
    [a, # a
     b], # b
  end
end

RuboCop version

$ bundle exec rubocop -V
0.40.0 (using Parser 2.3.1.0, running on ruby 2.3.1 x86_64-linux)