javascript Create Project Server Lookup Table

I'm trying to create a new lookup table in Project Server 2016 on prem from a SP hosted application using JSOM.

I have the following code:

private createLookupTables(): ng.IPromise<any> {
        var deferred = this.$q.defer();

        var projectContext = PS.ProjectContext.get_current();
        var lookupTables = projectContext.get_lookupTables();
        projectContext.load(lookupTables);

        projectContext.executeQueryAsync((sender, args) => {
            lookupTables.add(this.createLookupTable('54085ae0-d844-4c50-8835-c07e069cace2', 'test29'));
            lookupTables.update();
            projectContext.load(lookupTables);
            projectContext.executeQueryAsync((sender, args) => {
                deferred.resolve();
            }, (sender, args) => {
                deferred.reject(args.get_message());
            });
        }, (sender, args) => {
            deferred.reject(args.get_message());
        });

        return deferred.promise;
    }

    private createLookupTable(id: string, name: string): any {
        var lookupTableCreationInfo = new PS.LookupTableCreationInformation()
        lookupTableCreationInfo.set_id(id);
        lookupTableCreationInfo.set_name(name);
        lookupTableCreationInfo.set_sortOrder(0);

        var lookupMask = new PS.LookupMask();
        lookupMask.set_length(0);
        lookupMask.set_maskType(3);
        lookupMask.set_separator('.');
        lookupTableCreationInfo.set_masks(lookupMask);

        var entries = [];

        var ltEntry = new PS.LookupEntryCreationInformation();
        ltEntry.set_description("descr");
        ltEntry.set_sortIndex(1);
        ltEntry.set_id("7a6a9f6c-0987-4e72-887a-7cee1fdf9809")
        ltEntry.set_parentId(null);

        var ltValue = new PS.LookupEntryValue();
        ltValue.set_textValue("test");

        ltEntry.set_value(ltValue);
        entries.push(ltEntry);

        lookupTableCreationInfo.set_entries(entries);

        return lookupTableCreationInfo;
    }

What am I missing or doing wrong? Currently, the second executeQueryAsync call goes on the fail function with the error message being "Unknown error". Any ideas?