[BUG] KeyError raised if request is missing an expected param

[comhar]

Describe the bug A KeyError is raised whenever a request is made that is missing an expected param. This happens if the expected param is defined with or without a default value.

Minimal Reproducible Example Here's a minimal app.

from fasthtml.common import *

app,rt = fast_app(default_hdrs=False)

@rt
def check(p1:str='', p2:str=''): return Response(status_code=200)

serve(port=5000)

Here's some test code

import httpx

r = httpx.post('http://localhost:5000/check', json={'p1': 'val'}, headers={'Content-Type': 'application/json'})
print(r.status_code)

Running the test triggers KeyError: 'p2' and r has a 500 status code.

Expected behavior A KeyError should not be raised if a param is missing.

Environment Information Please provide the following version information:

• fastlite version: 0.1.2
• fastcore version: 1.8.0
• fasthtml version: 0.12.5

Confirmation Please confirm the following:

• [x] I have read the FAQ (https://docs.fastht.ml/explains/faq.html)
• [x] I have provided a minimal reproducible example
• [x] I have included the versions of fastlite, fastcore, and fasthtml
• [x] I understand that this is a volunteer open source project with no commercial support.

Additional context N/A

Screenshots N/A