optionparser_fail.cr

require "option_parser"

class Foo
  @filename : String
  def initialize(@filename)
  end
end

filename = nil

#OptionParser.parse! do |parser|
#  parser.on("-f FILE", "Filename") do |file|
#    filename = file
#  end
#end

if filename
  # if I uncomment the code above, this fails with:
  #   instance variable '@filename' of Foo must be String, not (String | Nil)
  Foo.new(filename)
end