This has come about from various discussions about there being little to no feedback when Heartbeat is unable to run a suite of Synthetics tests that have a ZIP URL for the source (e.g. an invalid configuration, or a syntax error in the ZIP). Part of this was also raised/discussed in elastic/beats#27924.

As a user of Synthetics suites with a ZIP URL source
I want to be informed in Uptime when there is a problem preventing the suite from running (such as a syntax error)
So that I can easily understand why monitors from the suite are not being shown on the Uptime Overview page

ACs:

• If Heartbeat is unable to execute the suite of tests as defined in a ZIP URL source, it stores this failure condition with some details about the failure, in ES
• This stored data does not interfere with any of the existing result data or alerting within Uptime
• There is a notification in the Uptime UI (such as a toast, or some other method), informing the user about the failure
  • The notification includes the details captured about the failure condition
  • There is no click through to more details, or see historic failures
• The user can dismiss the notification (there is no way to get back to it)
• Only show notifications for where the issue has occurred within the last x minutes (e.g. 30 minutes)