pyfetch: Do not raise an error on status code >= 400

docs/project/changelog.md

@@ -50,6 +50,10 @@ myst:
   `pyodide-lock.json`
   {pr}`3824`
 
+- {{ Breaking }} Changed the FetchResponse body getter methods to no longer
+  throw an OSError exception for 400 and above response status codes
+  {pr}`3986`
+
 ### Packages
 
 - OpenBLAS has been added and scipy now uses OpenBLAS rather than CLAPACK

src/py/pyodide/http.py

@@ -126,10 +126,6 @@ def url(self) -> str:
         return self.js_response.url
 
     def _raise_if_failed(self) -> None:
-        if self.js_response.status >= 400:
-            raise OSError(
-                f"Request for {self._url} failed with status {self.status}: {self.status_text}"
-            )
         if self.js_response.bodyUsed:
             raise OSError("Response body is already used")
 

src/tests/test_pyodide_http.py

@@ -2,6 +2,17 @@
 from pytest_pyodide import run_in_pyodide
 
 
+@pytest.fixture
+def url_notfound(httpserver):
+    httpserver.expect_request("/data").respond_with_data(
+        b"404 Not Found",
+        content_type="text/text",
+        headers={"Access-Control-Allow-Origin": "*"},
+        status=404,
+    )
+    return httpserver.url_for("/data")
+
+
 @pytest.mark.xfail_browsers(node="XMLHttpRequest is not available in node")
 def test_open_url(selenium, httpserver):
     httpserver.expect_request("/data").respond_with_data(
@@ -34,6 +45,15 @@ async def test_pyfetch_create_file(selenium):
     )
 
 
+@run_in_pyodide
+async def test_pyfetch_return_400_status_body(selenium, url_notfound):
+    from pyodide.http import pyfetch
+
+    resp = await pyfetch(url_notfound)
+    body = await resp.string()
+    assert body == "404 Not Found"
+
+
 @run_in_pyodide
 async def test_pyfetch_unpack_archive(selenium):
     import pathlib