fix exception message if filetype is unknown

Author: felixdivo

can/io/logger.py

@@ -65,4 +65,6 @@ def __new__(
         try:
             return lookup[suffix](filename, *args, **kwargs)
         except KeyError:
-            raise ValueError(f'No write support for this unknown log format "{suffix}"')
+            raise ValueError(
+                f'No write support for this unknown log format "{suffix}"'
+            ) from None

can/io/player.py

@@ -65,7 +65,9 @@ def __new__(cls, filename: "can.typechecking.PathLike", *args, **kwargs):
         try:
             return lookup[suffix](filename, *args, **kwargs)
         except KeyError:
-            raise ValueError(f'No read support for this unknown log format "{suffix}"')
+            raise ValueError(
+                f'No read support for this unknown log format "{suffix}"'
+            ) from None
 
 
 class MessageSync:  # pylint: disable=too-few-public-methods