Add error management to the REST builder

• Type: Story
• Status: Selected for Development
• Priority: Minor
• Resolution: Unresolved
• Affects Version/s: None
• Fix Version/s: None
• Component/s: Headless CMS
• Labels:
  • fc_20_02
• Epic/Theme:
  • Headless_Management
• Epic Link: Make REST builder usable by external developers

As an API developer

I want to have clear information about why the REST builder failed

so that I can fix it easily