Throw exception when there are no available seats for checkout

[nh314]

Debug mode

• I have enabled debug mode
• I have read checked the Common Issues page

Describe the bug

Throw exception when there are no available seats for checkout

Reproduction steps

1. Create new test license with 2 seats
2. Go to license software page, click 'Checkout' button of the license just created
3. On 'Checkout License Seat' page, select random user and click 'Checkout' button
4. Repeat step 2
5. Open new tab, edit the license, decrease number of seat to 1
6. Back to tab at step 4, select random user and click 'Checkout' button.

Expected behavior

Redirect to 'License Index' page with error message 'There are no available seats for this license'

Screenshots

Snipe-IT Version

6.0.8

Operating System

Ubuntu 22.04.1 LTS

Web Server

Apache/2.4.52 (Ubuntu)

PHP Version

Apache/2.4.52 (Ubuntu)

Operating System

No response

Browser

No response

Version

No response

Device

No response

Operating System

No response

Browser

No response

Version

No response

Error messages

No response

Additional context

No response

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