houses pset7 works fine with me but doesn't work when run through check50

the pset i'm working on has 2 parts, both of which work fine with me. however when i run these through check50 i would get 1/6. here is a link to what i should do in the pset: pset and these are the errors i get: errors.

here is my code for import.py:

from cs50 import SQL
from sys import argv, exit
import csv

db = SQL("sqlite:///students.db")

if len(argv) != 2:
    print("error")
    exit(1)
    
if argv[1] != "characters.csv":
    print("error")
    exit(1)
    
with open(argv[1], "r") as CSVfile:
    CSVfile = csv.DictReader(CSVfile, delimiter = ',')
    chars = list(CSVfile)
    
    for row in chars:
        name = row["name"]
        birth = row["birth"]
        house = row["house"]
        
        full = name.split( )
        
        if len(full) == 2:
            
            first = full[0]
            last = full[1]
            
            db.execute("INSERT INTO students(first, last, house, birth) VALUES(?, ?, ?, ?)", first, last, house, birth)
            
        elif len(full) == 3:
            
            first = full[0]
            middle = full[1]
            last = full[2]
            
            db.execute("INSERT INTO students(first, middle, last, house, birth) VALUES(?, ?, ?, ?, ?)", first, middle, last, house, birth)

here is my code for roster:

from cs50 import SQL
from sys import argv, exit
import csv

if len(argv) != 2:
    print("error")
    exit(1)
    
db = SQL("sqlite:///students.db")

results = db.execute("SELECT * FROM students WHERE house = ? ORDER BY last ASC, first ASC", argv[1])


for row in results:
    
    if 'middle' != None:
        print(f"{row['first']} {row['middle']} {row['last']}, born {row['birth']}")
    
    else:
        print(f"{row['first']} {row['last']}, born {row['birth']}")

i've already talked to a mentor about it and i've fixed the mistakes that he has mentioned so they're irrelevant. thanks in advance.

edit:

i removed this part:

if argv[1] != "characters.csv":
        print("error")
        exit(1)

as it is a mistake to hardcode the name of the csv file into my code. this has improved things a lot. however, i now have faced a problem in roster. what i meant to see as output was the student's full name and birth year. some students don't have a middle name so i tried to make an if condition to see if 'middle' exists in this name or not:

if 'middle' != None:
            print(f"{row['first']} {row['middle']} {row['last']}, born {row['birth']}")
        
        else:
            print(f"{row['first']} {row['last']}, born {row['birth']}")

however, what i would instead get as input for students with no middle name would be something like this: Lavender None Brown, born 1979