QUERY_STRING is assumed

According to https://github.com/jonashaag/bjoern/issues/118, QUERY_STRING cannot be assumed as part of the incoming environment.

Request.args and Request.json_args should assume QUERY_STRING="" when it is not present in the environment.

https://github.com/nullism/pycnic/blob/1e60f41d01a4940c5ade0e9d7981d5fa71af67bd/pycnic/core.py#L77-L96

Example application:

from pycnic.core import WSGI, Handler

class Hello(Handler):
    def get(self):
        name = self.request.args.get("name", "Pycnic")
        return {"msg": "Hello, %s!" % (name)}

class app(WSGI):
    routes = [("/hello", Hello())]

if __name__ == "__main__":
    import bjoern
    bjoern.run(app, "127.0.0.1", 8000)

When run, requests to http://localhost:8000 err:

'QUERY_STRING'
Traceback (most recent call last):
  File "/XXXX/lib/python3.8/site-packages/pycnic/core.py", line 237, in __iter__
    resp = self.delegate()
  File "/XXXX/lib/python3.8/site-packages/pycnic/core.py", line 310, in delegate
    output = func(*args)
  File "app.py", line 6, in get
    name = self.request.args.get("name", "Pycnic")
  File "/XXXX/lib/python3.8/site-packages/pycnic/core.py", line 81, in args
    qs = self.environ["QUERY_STRING"]
KeyError: 'QUERY_STRING'

[aronatkins]

@nullism - It appears as if QUERY_STRING is not assumed to be present according to the linked PEP. I encountered an unset QUERY_STRING when playing with bjoern; not sure if other servers act similarly.

[nullism]

Uploaded as v0.1.9