`Response.headers.get` does not type check with `pyright`s strict checking mode

[Unigurd]

Running pyright with strict checking will result in type errors in the reproduction script below because it cannot infer the return type of .get. I believe it's because CaseInsensitiveDict doesn't override .get and add type information like it does with the methods used for [] indexing.

Expected Result

I expect f2 to type check just like f1 does.

Actual Result

f2 fails to type check with the error message

/path/to/script.py
  /path/to/script.py:9:12 - error: Type of "get" is partially unknown
    Type of "get" is "Overload[(key: Unknown, /) -> (Unknown | None), (key: Unknown, /, default: Unknown) -> Unknown, (key: Unknown, /, default: _T@get) -> (Unknown | _T@get)]" (reportUnknownMemberType)
  /path/to/script.py:9:12 - error: Return type is unknown (reportUnknownVariableType)
2 errors, 0 warnings, 0 informations

Reproduction Steps

Install pyright 1.1.405, the latest as of this writing, and configure it to check strictly, e.g. with

[tool.pyright]
typeCheckingMode = "strict"

in your pyproject.toml.

Now running pyright on the following short script will result in the type checking errors.

import niquests

# Will pass pyright type check
def f1(resp: niquests.Response) -> str | bytes:
    return resp.headers["Content-Type"]

# Will fail pyright type check
def f2(resp: niquests.Response) -> str | bytes:
    return resp.headers.get("Content-Type", "")

System Information

$ python -m niquests.help

{
  "charset_normalizer": {
    "version": "3.4.0"
  },
  "gil": true,
  "http1": {
    "h11": "0.16.0"
  },
  "http2": {
    "jh2": "5.0.9"
  },
  "http3": {
    "enabled": true,
    "qh3": "1.5.4"
  },
  "idna": {
    "version": "3.10"
  },
  "implementation": {
    "name": "CPython",
    "version": "3.12.3"
  },
  "niquests": {
    "version": "3.15.2"
  },
  "ocsp": {
    "enabled": true
  },
  "platform": {
    "release": "6.6.87.2-microsoft-standard-WSL2",
    "system": "Linux"
  },
  "system_ssl": {
    "name": "OpenSSL 3.0.13 30 Jan 2024",
    "version": "300000d0"
  },
  "urllib3.future": {
    "cohabitation_version": null,
    "version": "2.13.906"
  },
  "wassima": {
    "version": "2.0.1"
  },
  "websocket": {
    "enabled": false,
    "wsproto": null
  }
}