Confusing error types

[laurentpayot]

[REQUIRED] Describe your environment

• Operating System version: Ubuntu 20.10
• Browser version: Chrome 96.0.4664.45 64b
• Firebase SDK version: 9.5.0
• Firebase Product: firestore, auth, storage

[REQUIRED] Describe the problem

To handle Firebase errors in a generic way I had to do dangerous type assertions to calm TypeScript down.

Firestore is a part of Firebase but, according to TypeScript, FirestoreError is not a FirebaseError.
But AuthError is a FirebaseError, just like StorageError (looks like at least).
But StorageError has a special attribute serverResponse, not nested into customData like AuthError does…
Wat?

Here are the incriminated TypeScript interfaces:

/** An error returned by a Firestore operation. */
export declare class FirestoreError extends Error {
    /**
     * The backend error code associated with this error.
     */
    readonly code: FirestoreErrorCode;
    /**
     * A custom error description.
     */
    readonly message: string;
    /** The custom name for all FirestoreErrors. */
    readonly name: string;
    /** The stack of the error. */
    readonly stack?: string;
    private constructor();
}

/**
 * Interface for an `Auth` error.
 *
 * @public
 */
export declare interface AuthError extends FirebaseError {
    /** Details about the Firebase Auth error.  */
    readonly customData: {
        /** The name of the Firebase App which triggered this error.  */
        readonly appName: string;
        /** The email address of the user's account, used for sign-in and linking. */
        readonly email?: string;
        /** The phone number of the user's account, used for sign-in and linking. */
        readonly phoneNumber?: string;
        /**
         * The tenant ID being used for sign-in and linking.
         *
         * @remarks
         * If you use {@link signInWithRedirect} to sign in,
         * you have to set the tenant ID on the {@link Auth} instance again as the tenant ID is not persisted
         * after redirection.
         */
        readonly tenantId?: string;
    };
}

/**
 * An error returned by the Firebase Storage SDK.
 * @public
 */
export declare interface StorageError {
    /**
     * A server response message for the error, if applicable.
     */
    serverResponse: string | null;
    code: string;
    customData?: Record<string, unknown>;
    name: 'FirebaseError';
    message: string;
    stack?: string;
}

export declare class FirebaseError extends Error {
    readonly code: string;
    customData?: Record<string, unknown> | undefined;
    readonly name = "FirebaseError";
    constructor(code: string, message: string, customData?: Record<string, unknown> | undefined);
}

So two little requests 🙏

1. Could it be possible for FirestoreError to actually be a FirebaseError just like other Firebase errors?
2. Would it be possible for all FirebaseError, including StorageError, to simply have code, name, message and stack attributes, and all other error details nested into customData (as it was done for AuthError)?

That would make my day.

Cheers,
Laurent

[wu-hui]

Hey @laurentpayot

Thanks for the request. We will look into this and see if we can improve.

[schmidt-sebastian]

PR is pending review (but almost everyone is out for the holidays)