message: Invalidate a Node trying to connect itself with the same handle
  It also be written as `!(elementBelowNodeId === nodeId && elementBelowHandleId === handleId)`
diff: @@ -60,7 +60,7 @@ export function checkElementBelowIsValid(
  const isValid =
  connectionMode === ConnectionMode.Strict
  ? (isTarget && elementBelowIsSource) || (!isTarget && elementBelowIsTarget)
  - : true;
  + : elementBelowNodeId !== nodeId || elementBelowHandleId !== handleId;
  if (isValid) {
  result.isValid = isValidConnection(connection);
  