TypeError: string indices must be integers

def load_data(self):        reviews = pd.read_csv('tuniu.csv')          data = reviews['content']        #with open('r.json') as file:           #data = file.read()        #data = json.loads(data)        #print(type(data))        return data    def fenci_data(self):            text = []            data = self.load_data()            with open("stoplist.txt", 'r',encoding='UTF-8') as file:                stop_word_list = file.read()            for weibo_item in tqdm(data):                tmp = []                sentence=''.join(re.findall(r'[\u4e00-\u9fa5]+',weibo_item['content']))                for word in jieba.lcut(sentence):                    if word not in stop_word_list:                        tmp.append(word)                text.append(tmp)            return text

Report errors ：
sentence=''.join(re.findall(r'[\u4e00-\u9fa5]+',weibo_item['content']))
TypeError: string indices must be integers