"During handling of the above exception, another exception occurred" - python-3.x

Question

I am reading from a file a list of fractions, and parsing them into a list of tuples. I want an error to occur if the file is empty or if the denominator is less than or equal to 0.
I've tried putting if(EOFERRor), elif(zerodivisionerror), elif(assertionerror), else.. inside the InvalidFile(Exception) class. Before my exception would raise for the end of the file read, so that's why I included that into it specifically.
My guess would be that EOF occurs at the same time as divide by zero, but I separated the list from the file to keep that from happening
class InvalidFile(Exception):
if(EOFError):
pass
else:
print('Invalid file format')
sys.exit(1)
def createFractionList(filePath):
try:
f = open(inFile)
f.close()
except FileNotFoundError:
print('FileNotFoundError')
sys.exit(1)
fractionList = []
for line in open(filePath):
line = line.rstrip()
try:
numerator, denominator = tuple(int(x) for x in line.split())
except:
raise InvalidFile
fractionList.append((numerator, denominator))
for lists in fractionList:
try:
lists[0]/lists[1]
except:
raise InvalidFile
return fractionList
dateList = createFractionList(inFile)
print(dateList)
INPUT:
1 0
3 4
5 6
7 8
9 10
0 8
2 4
9 12
20 24
35 40
54 60
Expected Output:
Invalid file format
Actual Output:
C:\Users\Xavier\PycharmProjects\hw4\venv\Scripts\python.exe C:/Users/Xavier/PycharmProjects/hw4/hw4.py
Traceback (most recent call last):
File "C:/Users/Xavier/PycharmProjects/hw4/hw4.py", line 33, in createFractionList
lists[1]/0
ZeroDivisionError: division by zero
During handling of the above exception, another exception occurred:

Answer 1

The body of your InvalidFile exception does nothing because it's only run at declaration. And in any case, if EOFError is always true, so nothing happens. What you should do is override the __init__ method with a custom text. Personally I don't think you need a custom exception, you can just use in-built ones instead.
Your first error is FileNotFoundError which you'd be better off checking with os.path.exists().
You should use a context manager when you open the file, then you don't need to worry about closing it.
You don't need to strip the line because `int('1 \n') already strips whitespace. But maybe the input file has blank lines, so we could keep this.
You don't need to loop through the file and then the lists, because if at any point, the denominator is less than or equal to 0 the error should be raised. There's no point delaying the error for later. And it seems there is no point doing the division either because you can work out in advance if it's going to fail.
So all in all, you could rewrite the code like this:
import os.path
def create_fraction_list(file_path):
if not os.path.exists(file_path):
raise FileNotFoundError(file_path)
fraction_list = []
with open(file_path) as f:
for line in f:
line = line.strip()
if not line:
# have a blank line
continue
numerator, denominator = (int(x) for x in line.split())
if denominator <= 0:
raise ValueError(f'Denominator less that or equal to 0: {numerator}/{denominator}')
fraction_list.append((numerator, denominator))
if not fraction_list:
# it's empty
raise ValueError(f'Input file has no valid lines: {file_path}')
return fraction_list
if __name__ == '__main__':
try:
fraction_list = create_fraction_list(inFile)
print(fraction_list)
except (FileNotFoundError, ValueError):
print('Invalid file format.')
sys.exit(1)