Remove raise from _ReadHeaders

The only caller to this method does handle exceptions from this method,
so instead of crashing, just log the message and continue processing

This is related to #1673

Author: sc68cal

ycmd/completers/language_server/language_server_completer.py

@@ -566,7 +566,6 @@ def _ReadHeaders( self, data ):
             except Exception:
               LOGGER.exception( 'Received invalid protocol data from server: '
                                  + str( line ) )
-              raise
 
         read_bytes += 1