Consistently close connection after ERROR frame

Closes gh-23039

Author: rstoyanchev

spring-websocket/src/main/java/org/springframework/web/socket/messaging/StompSubProtocolHandler.java

@@ -329,12 +329,10 @@ private void handleError(WebSocketSession session, Throwable ex, @Nullable Messa
 			sendErrorMessage(session, ex);
 			return;
 		}
-
 		Message<byte[]> message = getErrorHandler().handleClientMessageProcessingError(clientMessage, ex);
 		if (message == null) {
 			return;
 		}
-
 		StompHeaderAccessor accessor = MessageHeaderAccessor.getAccessor(message, StompHeaderAccessor.class);
 		Assert.state(accessor != null, "No StompHeaderAccessor");
 		sendToClient(session, accessor, message.getPayload());
@@ -357,6 +355,14 @@ private void sendErrorMessage(WebSocketSession session, Throwable error) {
 			// Could be part of normal workflow (e.g. browser tab closed)
 			logger.debug("Failed to send STOMP ERROR to client", ex);
 		}
+		finally {
+			try {
+				session.close(CloseStatus.PROTOCOL_ERROR);
+			}
+			catch (IOException ex) {
+				// Ignore
+			}
+		}
 	}
 
 	private boolean detectImmutableMessageInterceptor(MessageChannel channel) {