为什么我会遇到这个词性错误，我该如何解决

如何解决为什么我会遇到这个词性错误，我该如何解决

我正在尝试对文本进行词形还原，当我这样做时说：

KeyError: 'NNP'

我认为这是与专有名词词形还原有关的问题，不确定，非常感谢任何帮助

没有导入的完整代码：

lemmatizer = WordNetLemmatizer()
stop_words = set(stopwords.words('english'))

text = wikipediaTextProcessor("https://en.wikipedia.org/wiki/Pangolin")

tokenizedText = word_tokenize(text)
textNoStopwords = [word for word in tokenizedText if word not in stop_words]

posTaggedText = pos_tag(textNoStopwords)

lemmatizedText = []

for word,tag in posTaggedText:
    lemmatizedText.append(lemmatizer.lemmatize(word,tag))

print(lemmatizedText)

完全错误：

Traceback (most recent call last):
  File "c:\Users\nayna\Desktop\PangolinProject\NaturalLanguageProcessingFile.py",line 25,in <module>
    lemmatizedText.append(lemmatizer.lemmatize(word,tag))
  File "C:\Users\nayna\Desktop\PangolinProject\.venv\lib\site-packages\nltk\stem\wordnet.py",line 38,in lemmatize
    lemmas = wordnet._morphy(word,pos)
  File "C:\Users\nayna\Desktop\PangolinProject\.venv\lib\site-packages\nltk\corpus\reader\wordnet.py",line 1917,in _morphy
    exceptions = self._exception_map[pos]
KeyError: 'NNP'