add VBANCMDPacketError to exception hierarchy

raise them when we fail to validate incoming packets.

add VbanRTRequestHeader post_init to validate the provided bps value.

VbanRTSubscribeHeader and VbanRTRequestHeader properties now return int type. They are then directly packed into the header.

vban_cmd/error.py

@@ -1,6 +1,18 @@
+from .packet.enums import ServiceTypes, SubProtocols
+
+
 class VBANCMDError(Exception):
     """Base VBANCMD Exception class."""
 
 
 class VBANCMDConnectionError(VBANCMDError):
     """Exception raised when connection/timeout errors occur"""
+
+
+class VBANCMDPacketError(VBANCMDError):
+    """Exception raised when packet parsing errors occur"""
+
+    def __init__(self, message: str, protocol: SubProtocols, type_: ServiceTypes):
+        super().__init__(message)
+        self.protocol = protocol
+        self.type = type_