Fix type hint

sohstationviewer/model/reftek_data/reftek_reader/log_file_reader.py

@@ -7,7 +7,7 @@ RT130_PACKETS = ['SH', 'SC', 'OM', 'DS', 'AD', 'CD', 'FD', 'EH', 'ET']
 SeparatedPacketLines = Tuple[List[str], List[str], List[str]]
 
 
-def detect_log_file_packet_format(packet: List[str]) -> LogFileFormat:
+def detect_log_packet_format(packet: List[str]) -> Optional[LogFileFormat]:
     """
     Detect the format of a log file packet. The format can be either rt2ms',
     logpeek's, or SOHStationViewer's.
@@ -239,7 +239,7 @@ class LogFileReader:
         log_file = LogFile(self.file_path)
         for packet in log_file:
             if self.log_file_type is None:
-                self.log_file_type = detect_log_file_packet_format(packet)
+                self.log_file_type = detect_log_packet_format(packet)
 
             parser = PACKET_PARSERS[self.log_file_type]
             eh_et_lines, soh_lines, masspos_lines = parser(packet)