[UX IMPROVEMENT] Discriminate between error messages when trying to pay invoices

[PaulADW]

The app does not discriminate between "fixed amount invoices" and "variable amount invoices".
This leads to much confusion for users.

Here's an exemple : I send an invoice for 159 069 sats, the person that has to pay it copies and pastes the invoice in the app, here's what they see :

They get the possibility to enter an amount, even though the invoice they received is for a fixed amount. That is a bad UX. This is because the error message does not discriminate between Fixed amount invoices and Variable Amount Invoices.

The UX should say something like "This invoice is for 159 069 sats (98,61€), you don't have enough funds to pay it". Also you shouldn't be able to edit the amount you want if you're trying to pay a Fixed Amount Invoice, it doesn't make sense.

You guys should write a rule that would be like "IF INVOICED RECEIVED IS FIXED AMOUNT AND USER BALANCE IS INFERIROR TO INVOICE, THEN DISPLAY ERROR MESSAGE "YOU DONT HAVE ENOUGH MONEY TO PAY THIS INVOICE"

Here's how the user reacts with the current UX :

Shouldn't be hard to fix and make it much more user friendly.