no error message loading non-existent modules (only when multiple levels in the hierarchy have default symlinks?)

[bernstei]

Describe the bug

If a default symlink exists above the deepest level of a directory tree, lmod can end up substituting it for explicitly specified non-existent modules.

To Reproduce

Create the following directory tree

lmod_test_modules/:
t_dft/

lmod_test_modules/t_dft:
vasp/

lmod_test_modules/t_dft/vasp:
6.4.3/  default@

lmod_test_modules/t_dft/vasp/6.4.3:
default@  normal.lua  _test.lua

where the vasp/default symlink points to 6.4.3, and the 6.4.3/default symlink points to normal.lua. Now do

module use lmod_test_modules
module purge
module load t_dft/vasp/does_not_exist
module list

the output will show that it added t_dft/vasp/6.4.3/normal. That'd make sense to me if does_not_exist wasn't specified (because of the default symlink), but with it, I'd expect an error that this module does not exist. And indeed, doing module load t_dft/vasp/6.4.3/does_not_exist gives exactly the error I'd expect, so I suspect it has something to do with the default symlinks on multiple levels of the tree.

Expected behavior

An error message when trying to load a non-existent submodule directly under t_dft/vasp, like I get for t_dft/vasp/6.4.3/nonexistent

Desktop (please complete the following information):

• OS: Linux
• Rocky 8.10
• Lmod Version: Modules based on Lua: Version 8.7.55 (8.7.55-2-g1dce13cc) 2024-12-19 12:53 -05:00
• For Lmod Versions 8.7.7+, please run "module --miniConfig" and
  include the output here.

Modules based on Lua: Version 8.7.55 (8.7.55-2-g1dce13cc) 2024-12-19 12:53 -05:00
    by Robert McLay [email protected]

Lmod Version: 8.7.55-2-g1dce13cc
Lua Version:  5.3
MODULEPATH:   /home/cluster/bernstei/lmod_test_modules:/home/cluster/bernstei/a:/opt/local/lmod/modulefiles:/opt/ohpc/pub/modulefiles


Changes from Default Configuration
----------------------------------

Name                         Where Set  Default                                                               Value
----                         ---------  -------                                                               -----
LFS_VERSION                  D          1.6.3                                                                 1.8.0
LMOD_COLORIZE                E          yes                                                                   no
LMOD_LD_LIBRARY_PATH         E          false                                                                 /home/cluster/bernstei/.local/lib64:/opt/ohpc/pub/mpi/ucx-ohpc/1.15.0/lib:/opt/local/openmpi4/install/4.1.4/gnu/lib:/opt/intel/oneapi/mkl/2022.1.0/lib/intel64:/opt/ohpc/pub/compiler/gcc/12.4.0/lib64:/home/cluster/bernstei/lib:/share/apps/local/lib
LMOD_LD_PRELOAD              E          false                                                                 /opt/intel/oneapi/mkl/2022.1.0/lib/intel64/libmkl_gf_lp64.so:/opt/intel/oneapi/mkl/2022.1.0/lib/intel64/libmkl_sequential.so:/opt/intel/oneapi/mkl/2022.1.0/lib/intel64/libmkl_core.so
LMOD_PACKAGE_PATH            D          nil                                                                   <empty>
LMOD_PAGER                   C          less                                                                  /usr/bin/less
LMOD_SITEPACKAGE_LOCATION    Other      /home/cluster/bernstei/lmod_test/lmod/8.7.55/libexec/SitePackage.lua  <srctree>
LMOD_SYSTEM_DEFAULT_MODULES  D          __unknown__                                                           <empty>
LMOD_TCLSH                   C          tclsh                                                                 /home/Software/python/miniconda3/bin/tclsh
MODULEPATH_ROOT              C                                                                                /home/cluster/bernstei/lmod_test/modulefiles
PATH_TO_LUA                  C          lua                                                                   /usr/bin/lua


Where Set -> D: default, E: environment, C: configuration
             lmod_cfg: lmod_config.lua SitePkg: SitePackage StdPkg: StandardPackage
             Other: Set somewhere outside of normal locations