inconsistent use of tabs and spaces in indentation notepad++ Python

Question

I am getting an inconsistent use of tabs and spaces in indentation error after adding only one line of code and I can't see why it would throw the error, here is the code:

auth = tweepy.OAuthHandler(consumer_key, consumer_secret) #create authentcation handler

auth.set_access_token(access_token, access_secret) #set access tokens to connect to twitter dev account

api = tweepy.API(auth, wait_on_rate_limit=True, wait_on_rate_limit_notify=True) #consume tweepy api function, 

tweets = api.user_timeline('realDonaldTrump', count=30) 

tweets_list = []
for each_tweet in tweets:
    tweets_list.append(each_tweet._json)
with open('tweets.csv', 'a') as file:
        file.write(json.dumps(tweets_list, indent=4))

my_demo_list = []
with open('tweets.csv', encoding='utf-8') as csvFile:  
    all_data = json.load(csvFile)
    for json_tweet_data in all_data:
        tweet_id = json_tweet_data['id']
        text = json_tweet_data['text']
        favorite_count = json_tweet_data['favorite_count']
        retweet_count = json_tweet_data['retweet_count']
        created_at = json_tweet_data['created_at']
        #lang= json_tweet_data['lang']
        my_demo_list.append({'tweet_id': str(tweet_id),
                             'text': str(text),
                             'favorite_count': int(favorite_count),
                             'retweet_count': int(retweet_count),
                             'created_at': created_at,
                             'lang':str(lang)
                            })
        print(my_demo_list)
        tweet_json = pd.DataFrame(my_demo_list, columns = 
                                  ['tweet_id', 'text', 
                                   'favorite_count', 'retweet_count', 
                                   'created_at','language'])        
print(tweet_json)

the #lang = json_tweet_data['lang'] line is where the error is appearing and if I remove it or comment it out like it is in the code shown, it will work fine, from what I can see everything is indented fine, what could be the issue here?

Solution

It means exactly what is sounds like: you indented your code with spaces in some places and with tabs in others. To fix this, in Notepad++, go to Edit -> Blank Operations -> TAB to Space (PEP 8 recommends using spaces vs. tabs).