当我没有使用它时，我在randrange中创建列表和错误时会生成'NoneType'

Question

import random
foundwords = []
wordsDict = {}

with open("text", "r") as file:
    contents = file.read().replace('\n',' ')
words = contents.split(' ')

def findwords(word):
    for i in range(len(words) - 1):
        if words[i] == word:
            if not words[i + 1] == '':
                foundwords.append(words[i + 1])
    return foundwords

for word in words:
    wordsDict.setdefault(word, findwords(word))

# for i in range(len(words) - 1):
#     findwords(words[i])
#     wordsDict.setdefault(words[i], foundwords)
#     del foundwords[:]

def nextword(word):
    wordList = wordsDict.get(word.lower())
    new = wordList[random.randint(0, len(wordList) - 1)]
    return new

def assemble():
    final = [words[random.randint(0, len(words))].capitalize()]
    final.append(nextword(final[-1]))
    print(final)

assemble()

我试图创建一个马尔可夫链项目，但是，我收到以下错误：

Traceback (most recent call last):
  File "main.py", line 32, in <module>
    assemble()
  File "main.py", line 28, in assemble
    final.append(nextword(final[0]))
  File "main.py", line 23, in nextword
    new = wordList[random.randint(0, len(wordList) - 1)]
  File "/usr/local/lib/python3.6/random.py", line 220, in randint
    return self.randrange(a, b+1)
  File "/usr/local/lib/python3.6/random.py", line 198, in randrange
    raise ValueError("empty range for randrange() (%d,%d, %d)" % (istart, istop, width))
ValueError: empty range for randrange() (0,0, 0)
exited with non-zero status 

有时这个错误：

Traceback (most recent call last):
  File "main.py", line 31, in <module>
    assemble()
  File "main.py", line 28, in assemble
    final.append(nextword(final[0]))
  File "main.py", line 23, in nextword
    new = wordList[random.randint(0, len(wordList) - 1)]
TypeError: object of type 'NoneType' has no len()

我不知道如何开始解决这个问题。我只是一个初学程序员，所以如果我的代码效率低下或任何事情，我道歉。此外，我不确定这是否可以发布为一个问题，抱歉。