After submitting payment update is not installed

## Prerequisites
- [x] I have searched open and closed issues for duplicates.

## Describe the bug
I just paid for one app update twice because after I submitted my payment, no password prompt appeared, no installation proceeded and no email arrived on the first trial. I had one payment issue before (paying and succesfully installing app, but the payment was not deduced from my account) so I assumed it was a similar glitch. Only after checking my bank I found I actually paid twice. Only one email confirmation arrived so far.

Moreover, the update still didn't get through - I had to use `apt` in terminal to actually update the app.

### To Reproduce
Steps to reproduce the behavior:
1. Try to update some paid app that you didn't pay for yet
2. Submit the payment form.
3. No password prompt appears and/or the update is not installed.

### Expected behavior
Proceed with update after payment.

### Screenshots or screen recordings

### Logs

## Platform Information


- [ ] I'm using the latest version from git that I've manually compiled
- [x] I'm using the latest released stable version

## Additional context

Begin by reproducing the payment form flow for an unpaid app update and observe the handoff to installation, including the missing password prompt. Compare the payment, email confirmation, and installation outcomes; done means a paid update installs once after submission with the expected confirmation.

Written by the indexing model from the issue text.