Revert "Revert "Raise error when blf GzipFile is requested""

This reverts commit 4eaa7df.

Author: j-c-cook

can/io/blf.py

@@ -11,7 +11,7 @@
 of uncompressed data each. This data contains the actual CAN messages and other
 objects types.
 """
-
+import gzip
 import struct
 import zlib
 import datetime
@@ -395,6 +395,11 @@ def __init__(
             speed and compression (currently equivalent to level 6).
         """
         mode = "rb+" if append else "wb"
+        if type(file) == gzip.GzipFile:
+            raise ValueError(
+                f"The BLFWriter is currently incompatible with "
+                f"{gzip.GzipFile.__name__}s. Try using a different zip format."
+            )
         try:
             super().__init__(file, mode=mode)
         except FileNotFoundError: