[read_properties] skip unrecognized tags

klamath/elements.py

@@ -2,6 +2,7 @@
 Functionality for reading/writing elements (geometry, text labels,
  structure references) and associated properties.
 """
+import io
 from typing import IO, TypeVar
 from collections.abc import Mapping
 from abc import ABCMeta, abstractmethod
@@ -53,6 +54,8 @@ def read_properties(stream: IO[bytes]) -> dict[int, bytes]:
             if key in properties:
                 raise KlamathError(f'Duplicate property key: {key!r}')
             properties[key] = value
+        else:
+            stream.seek(size, io.SEEK_CUR)
         size, tag = Record.read_header(stream)
     return properties