NullPointerException in AbstractSchemaCreateor

[ithena]

The following line always causes a NullPointerexception since restriction.schema is null.

void createSimpleRestriction(BaseRestriction restriction, Context ctx) {
        if(restriction.base && restriction.base.namespaceURI != Consts.SCHEMA_NS) {
            restriction.schema.getType(restriction.base)?.create(this, ctx)
        }
    }