gh-125873: Improve error message when PYTHONHOME is invalid (#126027)

Co-authored-by: Lukasz Langa <ambv@meta.com>

Author: refeed

Misc/NEWS.d/next/Core_and_Builtins/2024-10-27-22-23-57.gh-issue-125873.BG97KU.rst

@@ -0,0 +1 @@
+Improved error message when an environment variable is misconfigured.

Python/codecs.c

@@ -1693,7 +1693,9 @@ _PyCodec_InitRegistry(PyInterpreterState *interp)
     if (mod == NULL) {
         PyThreadState *tstate = _PyThreadState_GET();
         _Py_DumpPathConfig(tstate);
-        return PyStatus_Error("Failed to import encodings module");
+        return PyStatus_Error("Failed to import encodings module. "
+                              "Your environment probably has misconfigured variables! "
+                              "Please check PYTHONHOME otherwise refer to `--help-env`");
     }
     Py_DECREF(mod);