bug: add a clear toast msg when a user is not registered

[MalekLahbib]

I was trying memeland locally and noticed that each time I try to upload a meme I have an error msg without an explanation, even in the console log:

and I understood the problem when I checked gnodev:

So I think it would be better for the user if a toast with a clear message is displayed.

[MalekLahbib]

I’m trying to add the feature I'm talking about by calling the 'isUserRegistered' function to do the verification once the adena wallet is connected, but I'm getting an error msg on the console :

Here's the code I added, it works well on my own front (GnoFundMe), but not with memeland:

[leohhhn]

Are you sure you are connecting to the proper RPC with the proper chainID?