[UI] "Send" dialog could give more feedback on what's wrong with BIP21 URI

[kristapsk]

Test URI - bitcoin:TB1QXJ6KVTE6URY2MX695METFTFT7LR5HYK4M3VT5F?amount=0.00100000&label=test&req-test=1.

Wasabi currently just says "Input a valid BTC address or URL." (which is URI, not URL, btw), without any details. In this case it's unknown required parameter req-test=1.

Also, I cannot see whole pasted URL, right arrow keys or End key doesn't help.

In comparison, sendpayment.py script of JoinMarket gives you the reason.

$ ./scripts/sendpayment.py testnet-test-123.jmdat "bitcoin:TB1QXJ6KVTE6URY2MX695METFTFT7LR5HYK4M3VT5F?amount=0.00100000&label=test&req-test=1"
User data location: /home/user/.joinmarket/
2023-12-27 19:19:19,474 [DEBUG]  rpc: getblockchaininfo []
2023-12-27 19:19:19,476 [DEBUG]  rpc: listwallets []
2023-12-27 19:19:19,476 [DEBUG]  rpc: getwalletinfo []
Traceback (most recent call last):
  File "/home/user/git/joinmarket-clientserver/./scripts/sendpayment.py", line 378, in <module>
    main()
  File "/home/user/git/joinmarket-clientserver/./scripts/sendpayment.py", line 74, in main
    parsed = btc.decode_bip21_uri(args[1])
  File "/home/user/git/joinmarket-clientserver/src/jmbitcoin/bip21.py", line 35, in decode_bip21_uri
    raise ValueError("Unknown required parameter " + key +
ValueError: Unknown required parameter req-test in BIP21 URI.

[kristapsk]

JoinmarketQt GUI also outputs the reason.

[kristapsk]

Also Blockstream Green.

[kristapsk]

Electrum didn't have check for this at all, implemented it recently (spesmilo/electrum#8789), error they give now is - "Unsupported key - req-test".