Fail loudly on unreadable config and empty library roots

Co-Authored-By: Claude Haiku 5.5 <noreply@anthropic.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/generat3d/config.py b/generat3d/config.py
index 9ea7266..804723f 100644
--- a/generat3d/config.py
+++ b/generat3d/config.py
@@ -39,6 +39,8 @@ def library_roots(cli_roots, path=None):
                 data = tomllib.load(f)
         except tomllib.TOMLDecodeError as e:
             raise Error(f"{path}: {e}") from None
+        except OSError as e:
+            raise Error(f"{path}: {e.strerror or e}") from None
         unknown = sorted(set(data) - KEYS)
         if unknown:
             raise Error(f"{path}: unknown keys: {', '.join(unknown)}")
@@ -49,6 +51,8 @@ def library_roots(cli_roots, path=None):
         raise Error(f"no library roots: pass -L or set library_roots in {path}")
     out = []
     for r in roots:
+        if not r.strip():
+            raise Error("empty library root")
         p = Path(r).expanduser()
         if not p.is_dir():
             raise Error(f"library root not found: {p}")