While doing Mutations, you might encounter some errors.

Prevent Errors:

There are a couple of ways to prevent errors from happening.

Check permissions:

Most of the object types — that are subject to permission checks — are linked to an ...Action object. This object will describe the different actions you can have on the given object.

For example, on the Story object you'll have the StoryActions object. If you want to delete a Story, you need to check if the delete field is true before using the storyDelete mutation.

Check for deprecations:

We might from time to time deprecate some fields. You should check every once in a while if some fields you are using are deprecated and/or will be removed in the future. As you might know, querying an inexistent field will crash the whole query.

Error Management

After checking all the above you still might encounter errors. Every mutation comes with an errors field. This field is an Array of errors that were found during the execution of your mutation. All errors in the array implement the MutationError interface.

It is recommended to query this field.

graphql
mutation storyBroadcast($input: StoryBroadcastInput!) {
    storyBroadcast(input: $input) {
        story {
            id
        }
        errors {
            __typename
            ... on MutationError {
                path
            }
            ... on ObjectNotFoundError {
                path
            }
        }
    }
}

Each mutation has a unique set of possible errors. Querying __typename shows which error occurred, and path describes the problematic field, for instance input.id. Providing a faulty story ID in the mutation above, you'll receive the following response

response
{
    "data": {
        "storyBroadcast": {
            "errors": [
                {
                    "__typename": "ObjectNotFoundError",
                    "path": "input.id"
                }
            ],
            "story": null
        }
    }
}

Here you notice the ObjectNotFoundError and "path": "input.id" describing that the provided id was not found.