add check for contractItemID validity to prevent 500

[usamabinnadeem-10]

Done

• Add a check for contractItemID query parameter when scheduling an exam to prevent 500 error

QA

• Check out this feature branch
• Run the site using the command ./run serve or dotrun
• View the site locally in your web browser at: http://0.0.0.0:8001/
  • Be sure to test on mobile, tablet and desktop screen sizes
• Purchase and schedule an exam and it should go through

Issue / Card

Fixes WD-16047

Help

QA steps - Commit guidelines

[webteam-app]

Demo

Jenkins

demos.haus

[abhigyanghosh30]

This is not relevant to the error btw

[abhigyanghosh30]

The error is here https://sentry.is.canonical.com/canonical/ubuntu-com/issues/93025/?query=is%3Aunresolved%20cred

[usamabinnadeem-10]

@abhigyanghosh30 the error is related to the contractItemID being an empty string. Previously the id was being read from the form but now I am extracting that directly from the query and if it is not present we show an error and don't schedule the exam in that scenario.