Python - TypeError: 'NoneType' object is not iterable

Question

I am attempting to prevent the input of anything other than an integer for an average, but I keep receiving a Traceback for a TypeError. Below is my program, and the program output when attempting to input anything other than an int for an average:

grades_file = open('grades.txt', 'w')

def get_averages():
    student = 1
    for i in range(3):
        name, average = get_name_average()
        student += 1
        grades_file = open('grades.txt', 'a')
        grades_file.write("Student Name: " + name + '\n' + "Student Average: " + str(average) + '\n\n')
        grades_file.close()
        print(("Added %s's average of %i to the file 'grades.txt. You are now entering information for student %i of 12.") % (name, average, student))
def get_name_average():
    student_name = input("Please enter the student's name: ")
    try:
        student_average = int(input(("Please enter the average for %s: ") % student_name))
        verified_average = check_grade_input(student_average)
        return student_name, verified_average
    except ValueError:
        print("ERROR!! Please enter grade value as an integer!")
    except TypeError:
        print('Type error too!')

def check_grade_input(average):
    legal_input = False
    while not legal_input:
        if (average < 0):
            print("Nah bro,  invalid number...")
            average = int(input("Please enter another average that is above 0: "))
        elif (average > 100):
            print("Nah bro,  invalid number...")
            average = int(input("Please enter another average that is below 100: "))
        else:
            return average

def show_grades_file():
    grades_file = open('grades.txt', 'r')
    grade_contents = grades_file.read()
    grades_file.close()
    print("\nThe information you entered for into file 'grades.txt' is:\n\n" + grade_contents)

def main():
    get_averages()
    show_grades_file()

main()

Traceback and input:

Please enter the student's name: Aaron
Please enter the average for Aaron: as
ERROR!! Please enter grade value as an integer!
Traceback (most recent call last):
  File "Documents/ProgrammingFundamentals/Lab6/aaron_blakey_Lab6b.py", line 52, in <module>
    main()
  File "Documents/ProgrammingFundamentals/Lab6/aaron_blakey_Lab6b.py", line 49, in main
    get_averages()
  File "Documents/ProgrammingFundamentals/Lab6/aaron_blakey_Lab6b.py", line 13, in get_averages
    name, average = get_name_average()
TypeError: 'NoneType' object is not iterable

Answer 1

In function get_name_average you have printed message in Exception part print("ERROR!! Please enter grade value as an integer!") and you did not return any value.

By default system will return none value & required two values name, average.

You need to follow below code.

def get_name_average():
    student_name = input("Please enter the student's name: ")
    try:
        student_average = int(input(("Please enter the average for %s: ") % student_name))
        verified_average = check_grade_input(student_average)
        return student_name, verified_average
    except ValueError:
        print("ERROR!! Please enter grade value as an integer!")
        return False,False
    except TypeError:
        print('Type error too!')
        return False,False

After that if you got exception then name,average=False,False.

In function get_averages you need add one condition if name is False then system should not write in the file.

This may help you.