**Describe the bug** Currently the `addGlobalContexts` function does not allow for typed `SelfDescribingJSON` schemas to be added. **To Reproduce** https://github.com/snowplow/snowplow-javascript-tracker/assets/15251081/4b4ed24f-5bdd-4184-8871-1f658b17453c **Expected behavior** The `addGlobalContexts` function allows for proper `SelfDescribingJSON` objects to be passed to it.