Remove assert and just log error on invalid packet

Should help with stability as reported here: kevinvincent#114 (comment)
Thanks to @raetha for this contribution.

custom_components/wyzesense/wyzesense_custom.py

@@ -126,10 +126,12 @@ def Parse(cls, s):
             assert len(s) >= 7
             s = s[:7]
             payload = MAKE_CMD(cmd_type, b2)
-        else:
-            assert len(s) >= b2 + 4
+        elif len(s) >= b2 + 4:
             s = s[: b2 + 4]
             payload = s[5:-2]
+        else:
+            log.error("Invalid packet: %s", bytes_to_hex(s))
+            return None
 
         cs_remote = (s[-2] << 8) | s[-1]
         cs_local = checksum_from_bytes(s[:-2])