[Tutor] randomly generated error

[Freedom Peacemaker]

Hi,
main idea was to :
- get random characters word
- randomly colour letters in my word
- from this coloured word print all yellow letters

As it is random i need to be sure that at least one letter is yellow so i
put yellow color into final variable. This code works but randomly
generates error. And i have no idea how solve this problem. Please help me

Traceback (most recent call last):
  File "proj3", line 23, in <module>
    w = "".join((colorpass[i.end()]) for i in re.finditer(re.escape(Y),
colorpass))
  File "proj3", line 23, in <genexpr>
    w = "".join((colorpass[i.end()]) for i in re.finditer(re.escape(Y),
colorpass))
IndexError: string index out of range

This is my code:

from random import choice
from string import ascii_letters, digits
import re

chars = ascii_letters + digits

word = "".join([choice(chars) for i in range(10)])

R = '\033[31m'  # red
G = '\033[32m'  # green
B = '\033[34m'  # blue
P = '\033[35m'  # purple
Y = '\033[93m'  # yellow

colors = [R, G, B, P, Y]

colorpass = "\033[93m"
for char in word:
    colorpass += char + choice(colors)
print(colorpass)

w = "".join((colorpass[i.end()]) for i in re.finditer(re.escape(Y),
colorpass))
print(w)

I am using Python 3.5.2 on Ubuntu 16.04