Remove dead code

I have tried to remove the .egg-link
(in which case the package is not considered editable),
and removing the package while leaving the .egg-link
(in which case the package is not shown).
I could not produce this "Editable install not found" message
with pip 21.2.

So I think this is dead code and I'm replacing this test by an assert.

src/pip/_internal/operations/freeze.py

@@ -170,15 +170,7 @@ def _get_editable_info(dist: BaseDistribution) -> _EditableInfo:
     if not dist.editable:
         return _EditableInfo(requirement=None, editable=False, comments=[])
     editable_project_location = dist.editable_project_location
-    if editable_project_location is None:
-        display = _format_as_name_version(dist)
-        logger.warning("Editable requirement not found on disk: %s", display)
-        return _EditableInfo(
-            requirement=None,
-            editable=True,
-            comments=[f"# Editable install not found ({display})"],
-        )
-
+    assert editable_project_location
     location = os.path.normcase(os.path.abspath(editable_project_location))
 
     from pip._internal.vcs import RemoteNotFoundError, RemoteNotValidError, vcs