Don't crash when a texture is on a disconnected HDD.

korman/exporter/image.py

@@ -143,7 +143,12 @@ class ImageCache:
             # the string "//". There isn't much we can do with that, unless the user
             # happens to have an unpacked copy lying around somewheres...
             path = Path(bl_image.filepath_from_user())
-            if path.is_file():
+            try:
+                exists = path.is_file()
+            except OSError:
+                exists = False
+            finally:
+                if exists:
                     cached_image.modify_time = path.stat().st_mtime
                     if cached_image.export_time and cached_image.export_time < cached_image.modify_time:
                         return None