Today I lost 0.05 eth for the error transactions

Me too
It's not new like every move in etherdelta has a fee and even it's still has an error it will cost you s fee plus the congested network recently so maybe we should not use etherdelta for the meantime and just wait for it to go back to normal. But if you still wanna use their platform then you should have at least 0.2eth in your wallet, just to be sure.