I am working with a generated complex type that is rather big. I need to check if certain properties exists on the type with create a variable and initializing all its properties to default/null values, since that would be too much work.

Is there a way to check if properties exists directly on type without instantiating them or creating a variable with all its properties and checking against it?
ex:
Assuming I have the following

    export type Mutations {
        upsertItem: {},
        upsertItemMany: {},
        removeItem: {},
        removeItemMany: {},
        upsertCustomer: {},
        upsertCustomerMany: {},
        removeCustomer: {},
        removeCustomerMany: {},
        ... (1000+ more properties exist)
    }

I tried to do something like:

    var mutations: Mutations;
    Object.hasOwn(mutations, 'upsertItem');

But all I get is the following error:
“Cannot convert undefined or null to object”

and if I try to initialize the variable like

    let mutations: Mutation = {};

I get an error that I need to specify all its properties which defeats the purpose.

I am guessing this can be solved using reflections but I don’t know how.