[Feature]: Display useful message when CJIT flow is unusable

[catch-21]

Describe the problem

The CJIT flow for funding spending balance is currently not working, see #2395.

Looking at the attached videos in the bug, unless you have experience with this flow it is not obvious that there is a problem, which leads to confusion about what the user can do in this scenario.

Describe the solution

It would be a better experience if, in the unlikely event that there is a problem with Bitkit proceeding through the CJIT flow, an error message is displayed explaining there is an internal error and prevent the user from proceeding. We could suggest to contact support or try again later.

Additional context

No response