Error Handling

Sentinel defines sentinel errors in the root sentinel package. All errors are created with errors.New and can be checked with errors.Is.

Store errors01

Error	Description
`ErrNoStore`	No store was configured on the engine
`ErrStoreClosed`	The store has been closed
`ErrMigrationFailed`	Database migration failed

Error	Description
`ErrSuiteNotFound`	Suite with the given ID does not exist
`ErrCaseNotFound`	Case with the given ID does not exist
`ErrRunNotFound`	Run with the given ID does not exist
`ErrBaselineNotFound`	Baseline with the given ID does not exist
`ErrPromptVersionNotFound`	Prompt version with the given ID does not exist

Error	Description
`ErrSuiteAlreadyExists`	A suite with the same name already exists in this app

Error	Description
`ErrNoTarget`	No target configured for the evaluation
`ErrNoScorers`	No scorers configured for the case

Store implementations wrap these sentinel errors with additional context:

return fmt.Errorf("postgres: get suite %s: %w", suiteID, sentinel.ErrSuiteNotFound)

Check errors using errors.Is:

s, err := eng.GetSuite(ctx, suiteID)
if errors.Is(err, sentinel.ErrSuiteNotFound) {
    // handle not found
}

The HTTP API maps sentinel errors to HTTP status codes:

Sentinel error	HTTP status
`ErrSuiteNotFound`, `ErrCaseNotFound`, etc.	`404 Not Found`
`ErrSuiteAlreadyExists`	`409 Conflict`
`ErrInvalidState`, `ErrEmptyInput`	`400 Bad Request`
`ErrNoStore`	`500 Internal Server Error`