KeyError: “None of [['' '']] are in the [columns]” pandas python

I need to make a program that read an excel file, take the columns by the user input and makes some simple graphs, I don't care about the axis scale. Here's my code for now:

import pandas as pd
import sys
import os
import plotly.express as px
import plotly.graph_objects as go

this is make the user input the excel file and convert it to pandas dataframe

def choose_file():
  global filepath
  filepath = input('Enter filepath: ')    
  assert os.path.exists(filepath), "I did not find the file at, " + str(filepath)
  f = open(filepath, 'r+')
  print("Hooray we found your file!")   
  f.close()   

def open_file():
  global file
  file = pd.read_csv(filepath, encoding='latin1', delimiter=',')  
  print(file.columns)   

this will make the user choose the columns and put them in a list

def choose_columns():
  global column_list
  global file
  column_list = []  
  needs_items = True
  while needs_items == True:   
    user_input = input('Select the columns: ')
    column_list.append(user_input)
    for user_input in column_list:
        print('- ' + user_input)   
    answer = input("Add another item? (y/n)  ")
    if answer == "n":
        needs_items = False
        print('Final list: ', column_list)
file = file[column_list] 
print(file)

def build_graph():
  global file
  df = file[[column_list]].plot()
  df.show()

choose_file()
open_file()
choose_columns()
build_graph()

I have been using the famous dataset Titanic from Kaggle and in choose_columns() I pick the columns 'PassengerID' and 'Survived'. But I'm getting this error:

 `KeyError: "None of [Index([('PassengerId', 'Survived')], dtype='object')] are in the [columns]"

How can I fix this and can someone explain to me why this is happening?