Setting custom BOARD_ROOT raises FileNotFoundError

[5frank]

zephyr/scripts/list_boards.py

Line 78 in 63972d6

for maybe_board in (boards / arch).iterdir():

above fails with error FileNotFoundError: [Errno 2] No such file or directory: when trying to set custom BOARD_ROOT to a directory that do not have all arches.
This would fix it, but not sure if setting BOARD_ROOT is deprecated or bad practice?

 def find_arch2board_set_in(root, arches):
     ret = defaultdict(set)
     boards = root / 'boards'
 
     for arch in arches:
-        for maybe_board in (boards / arch).iterdir():
+        arch_dir = (boards / arch)
+        if not arch_dir.is_dir():
+           continue
+        for maybe_board in arch_dir.iterdir():
             if not maybe_board.is_dir():
                 continue
             for maybe_defconfig in maybe_board.iterdir():

I am also curious why the west --board option can not be a path? It seems to me that having a unique identifier string for every board will cause conflicts and limits the use of sub-directories like zephyr/arm/nucleo/<model>.

[5frank]

This was caused by a incorrectly configured build environment.