gh-125873: Improve error message when PYTHONHOME is invalid

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 ``PYTHONHOME`` is invalid

Python/codecs.c

@@ -1526,7 +1526,7 @@ _PyCodec_InitRegistry(PyInterpreterState *interp)
     // search functions, so this is done after everything else is initialized.
     PyObject *mod = PyImport_ImportModule("encodings");
     if (mod == NULL) {
-        return PyStatus_Error("Failed to import encodings module");
+        return PyStatus_Error("Failed to import encodings module. Are you sure PYTHONHOME is correct?");
     }
     Py_DECREF(mod);