Throw a user-facing error

When running Functions in other parts of the platform, such as Workshop or Actions, you may want to throw an error with a detailed message. To do so, throw a UserFacingError from the @foundry/functions-api package. For example:

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    import { Edits, OntologyEditFunction, UserFacingError } from "@foundry/functions-api";
    import { Employee } from "@foundry/ontology-api";

    @Edits(Employee)
    @OntologyEditFunction()
    public editExactlyFiveEmployees(employees: Employee[]): void {
        if (employees.length != 5) {
            throw new UserFacingError(`Pass in exactly 5 employees. Received ${employees.length}.`);
        }
        ...
    }

When running this as a Function-backed Action in a Workshop application with an incorrect number of employees, users will see the following error:

By adding a detailed user facing error message, you can help other users of your Function quickly identify and fix the issue.