`utils.get_value` raise TypeError with out-of-range `int` index

[thanhlecongg]

Issue Description

When passing an out-of-range int index to utils.get_value, a TypeError is raised instead of returning the provided default value. Based on the documentation and function’s behavior in string cases, I’d expect it to fall back to default when the index is invalid. FYI, this issue seems to occur because handling IndexError requires falling back to getattr(obj, key, default). This logic was introduced in PR #1063 following git blame. I think this issue can be fixed by handling this TypeError to return default value. I can make an PR if this change make sense to you.

Reproducing Code Example

from marshmallow import utils

### Case 1: List
lst = [0, 1, 2, 3, 4, 5]
print(utils.get_value(lst, 999, default=3))

### Case 1: Dictionary with integer keys
dictionary = {1: 'a', 2: 'b', 3: 'c'}
print(utils.get_value(dictionary, 4, default='z'))

### Case 3: List of object
class PointClass:
    def __init__(self, x, y):
        self.x = x
        self.y = y

list_obj = [[PointClass(24, 42),{"x": 24, "y": 42}]]
print(utils.get_value(list_obj, 3, default=None))

Expected Result

Case 1: 3
Case 2: z
Case 3: None

Actual Behavior

Traceback (most recent call last):
  File "test.py", line 3, in <module>
    print(utils.get_value(lst, 999, default=3))
  File ".../site-packages/marshmallow/utils.py", line 108, in get_value
    return _get_value_for_key(obj, key, default)
  File ".../site-packages/marshmallow/utils.py", line 126, in _get_value_for_key
    return getattr(obj, key, default)
TypeError: getattr(): attribute name must be string

[deckar01]

get_value is only used to serialize data from the output of Schema.load(). Since enveloping the output with classes is a documented use case, it also handles class attributes. Schema.get_attribute() was designed to be overridden to provide an accessor for other types of envelopes (like lists).

We should consider breaking the attribute accessor out into a separate utility that users have to opt into. Toasted dropped attribute access as one of its primary optimizations.

We should probably also change the list test from (#340). That PR didn't add support for lists.