Program starts with error: something with 'encode' method and Windows-1251 and UTF-8 encodings in ruby ​​on rails?

Question

Ruby on Rails

def get_letters
slovo = ARGV[0]
if (Gem.win_platform? && ARGV[0])
slovo = slovo.encode(ARGV[0].encoding, "cp1251").encode("UTF-8")
end
if (slovo == nil || slovo == "")
abort "You didn't enter a word for the game"
end
return slovo.split("")
end
def get_user_input
letter = ""
while letter == "" do
letter = STDIN.gets.encode ("UTF-8").chomp
end
return letter
end
def check_result(user_input, letters, good_letters, bad_letters)
if (good_letters.include?(user_input) ||
bad_letters.include?(user_input))
return 0
end
if letters.include? user_input
good_letters << user_input
# condition when the whole word is guessed!
if letters.uniq.size == good_letters.size
return 1
else
return 0
end
else
bad_letters << user_input
return -1
end
end
def get_word_for_print(letters, good_letters)
result = ""
for letters in letters do
if good_letters.include? letter
result += letter + " "
else
result += "__ " end
end
return
result
end
#2.error information and already named letters
#3.errors > 7 - report defeat
#4.word guessed - report victory
def print_status(letters, good_letters, bad_letters, errors)
puts "\nWord: " + get_word_for_print(letters , good_Letters)
puts "Errors (#{errors}): #{bad_letters.join(", ")}"
if errors >= 7
puts "You lost :("
else
if letters.uniq.size == good_letters.size
puts " Congratulations! You win!\n\n"
else
puts " You have attempts left: " + (7-errors).to_s
end
end
end
def cls
system "clear"or system "cls"
end