How could it even work though from a legal point of view?
Legislation has been passed, we leave on to WTO trade terms in parliament does nothing. I don't see how this amendment changes that.
We already know 500/650 MPs do not support no deal. If those MPs can pass this amendment then they can also stop no deal happening anyway so it's pointless.
If an amendment passes blocking no deal it does to the best of my knowledge change things....
Please keep in mind I am pretty sure there would be legal challenges and a lot of parliament protocol to wade through... But in essence I think this is what then happens
The government is compelled to take all actions in its power to prevent a no deal and if they are seen not to then an MP could raise a motion forcing a vote upon specific action
They could also hold the government in contempt of parliament
All actions are basically
1.Pursue new deal (EU dependent and the EU wont)
2. Force a vote to make the government apply to extend A50... Likley EU says only for a ge or a 2nd ref... (Would need 2/3 votes to force ge so won't happen... But could force a yes no vote on a second ref)
3. If it gets to a few days before march 29th they could force a straight vote to cancel A50 unilaterally
Basically to stop this the government would have to submit a plan that said leave with no deal and get a commons majority for it
Essentially it takes the narrative and options away from the government... Of course somebody would have to find a majority for extend A50 or even cancel A50 but with 20 or so remain conservatives then it's far more likley than the government passing a no deal majority