Improve error reporting when None is mistakenly passed as a URL on client requests

[liberforce]

Long story short

While reusing some code I didn't notice that it required an environment variable to be defined.
This led to the URL used for the requests being None. However, calling ClientSession.request with str_or_url equal to None doesn't trigger an InvalidURL exception, but a TypeError on URL(str_or_url).

https://github.com/aio-libs/aiohttp/blob/master/aiohttp/client.py#L361

Expected behaviour

Consider None as an invalid URL and raise an according exception (InvalidURL)

Actual behaviour

TypeError is rased in yarl.URL.__new__

Steps to reproduce

Call ClientSession.request(method='GET', str_or_url=None, ...)

Your environment

Python 3.7 and aiohttp 3.5.2 in a virtualenv.
Running Ubuntu 18.04.
client.

[aio-libs-bot]

GitMate.io thinks the contributor most likely able to help you is @asvetlov.

Possibly related issues are #3242 (Error), #875 (Improve Request.repr), #2865 (Improve client timeouts), #3302 (Request json raises error if no arguments passed), and #3424 (Request url of client session gets malformed).

[asvetlov]

I think TypeError is pretty common exception for invalid argument type.
InvalidURL is a kind of ValueError which is raised when the type is correct but the value is not.

>>> int("10")
10
>>> int("not-valid")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: invalid literal for int() with base 10: 'not-valid'
>>> int(None)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: int() argument must be a string, a bytes-like object or a number, not 'NoneType'

[liberforce]

Right, it's just that having a wrong type also has the consequence of producing and invalid URL, so maybe raising an InvalidURL exception would be a better hint of what is wrong. Or maybe not, as the TypeError is more precise.

[lock]

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