ExCoveralls failing when reporting test coverage to Coveralls

[AndrewDryga]

We have an umbrella application and each app has test_coverage[:tool] set, but CI task which reports to coveralls started to crash:

Finished in 2.2 seconds
35 tests, 0 failures, 2 excluded

Randomized with seed 308035
** (Regex.CompileError) nothing to repeat at position 6
    (elixir 1.11.2) lib/regex.ex:216: Regex.compile!/2
    (elixir 1.11.2) lib/enum.ex:1399: Enum."-map/2-lists^map/1-0-"/2
    lib/excoveralls/stats.ex:130: ExCoveralls.Stats.skip_files/1
    lib/excoveralls/stats.ex:31: ExCoveralls.Stats.report/1
    lib/excoveralls.ex:43: ExCoveralls.execute/2
    (mix 1.11.2) lib/mix/tasks/test.ex:373: Mix.Tasks.Test.do_run/3
    (mix 1.11.2) lib/mix/task.ex:394: Mix.Task.run_task/3
    (mix 1.11.2) lib/mix/project.ex:352: Mix.Project.in_project/4
    (elixir 1.11.2) lib/file.ex:1552: File.cd!/2
    (mix 1.11.2) lib/mix/task.ex:511: anonymous fn/4 in Mix.Task.recur/1
    (elixir 1.11.2) lib/enum.ex:2181: Enum."-reduce/3-lists^foldl/2-0-"/3
    (mix 1.11.2) lib/mix/task.ex:510: Mix.Task.recur/1
    (mix 1.11.2) lib/mix/project_stack.ex:181: Mix.ProjectStack.recur/1
    (mix 1.11.2) lib/mix/task.ex:439: Mix.Task.run_alias/5
    lib/mix/tasks.ex:54: Mix.Tasks.Coveralls.do_run/2
    (mix 1.11.2) lib/mix/task.ex:394: Mix.Task.run_task/3
    (mix 1.11.2) lib/mix/cli.ex:84: Mix.CLI.run_task/2

and coveralls.json file in app which fails:

{
  "skip_files": [
    "apps/**/test/*",
    "config/*",
    "apps/**/config/*",
    "*.exs",
    "release_tasks.ex"
  ],
  "custom_stop_words": [
    "field",
    "has_one",
    "has_many",
    "embeds_one",
    "embeds_many",
    "schema",
    "send"
  ],
  "coverage_options": {
    "treat_no_relevant_lines_as_covered": true,
    "output_dir": "../../cover/notifications"
  }
}

Elixir 1.11.2 / OTP 23.1.4 / ExCoveralls 0.13.3.