Whats a good design/approach?

[snippsat]

Is approach1 is better approach 2

Both work in this case,approach 2 you can modify the error message.
It's not unclear what happen here in the case without try,except.

def _open(config):
    with open(config, "r") as fh:
        return fh.read()

>>> _open('foo.txt')
'hello'

>>> _open('foo999.txt')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "file_try.py", line 3, in _open
    with open(config, "r") as fh:
FileNotFoundError: [Errno 2] No such file or directory: 'foo999.txt'

[Errno 2] No such file or directory: 'foo999.txt'

Shorter just print the error from last line over.

def _open(config):
    try:
        with open(config, "r") as fh:
            return fh.read()
    except OSError as err:
        print(err)

>>> _open('foo.txt')
'hello'

>>> _open('foo999.txt')
[Errno 2] No such file or directory: 'foo999.txt'