Don't mention cors when failing to find wheel in emfs

micropip/wheelinfo.py

@@ -207,13 +207,14 @@ async def _fetch_bytes(self, url: str, fetch_kwargs: dict[str, Any]):
                 "cdn.jsdelivr.net",
             ]:
                 raise e
-            else:
+            if self.parsed_url.scheme in ("https", "http"):
                 raise ValueError(
                     f"Can't fetch wheel from {url!r}. "
                     "One common reason for this is when the server blocks "
                     "Cross-Origin Resource Sharing (CORS). "
                     "Check if the server is sending the correct 'Access-Control-Allow-Origin' header."
                 ) from e
+            raise e
 
     def _extract(self, target: Path) -> None:
         assert self._data

tests/test_install.py

@@ -355,6 +355,16 @@ async def run_test(selenium, url, wheel_name):
     run_test(selenium_standalone_micropip, snowball_wheel.url, snowball_wheel.filename)
 
 
+def test_emfs_error(selenium_standalone_micropip):
+    @run_in_pyodide()
+    async def run_test(selenium):
+        import micropip
+
+        await micropip.install("emfs:a-2.0.2-cp312-cp312-pyodide_2024_0_wasm32.whl")
+
+    run_test(selenium_standalone_micropip)
+
+
 def test_logging(selenium_standalone_micropip, wheel_catalog):
     @run_in_pyodide(packages=["micropip"])
     async def run_test(selenium, url, name, version):