apollo-client: Getting Store Errors after upgrading to v1.0.0

Since upgrading from a previous release candidate (rc6), I am now getting errors when running ALL of my create/delete mutations, regardless of what data they mutate I always get the same error:

Allergen.jsx:38 Error: Error: Store error: the application attempted to write an object with no provided id but the store already contains an id of Site:developer for this object.
    at writeFieldToStore (http://localhost:3000/packages/modules.js?hash=c1dea742144f5f0b244684fb3a95fddf714f326e:49816:23)
    at http://localhost:3000/packages/modules.js?hash=c1dea742144f5f0b244684fb3a95fddf714f326e:49709:17
    at Array.forEach (native)
    at writeSelectionSetToStore (http://localhost:3000/packages/modules.js?hash=c1dea742144f5f0b244684fb3a95fddf714f326e:49703:29)
    at writeResultToStore (http://localhost:3000/packages/modules.js?hash=c1dea742144f5f0b244684fb3a95fddf714f326e:49688:12)
    at http://localhost:3000/packages/modules.js?hash=c1dea742144f5f0b244684fb3a95fddf714f326e:51277:20
    at http://localhost:3000/packages/modules.js?hash=c1dea742144f5f0b244684fb3a95fddf714f326e:50464:34
    at Array.forEach (native)
    at data (http://localhost:3000/packages/modules.js?hash=c1dea742144f5f0b244684fb3a95fddf714f326e:50463:43)
    at apolloReducer (http://localhost:3000/packages/modules.js?hash=c1dea742144f5f0b244684fb3a95fddf714f326e:50675:23)
(anonymous) @ Allergen.jsx:38
(anonymous) @ meteor.js?hash=27829e9…:1105

In this particular instance I was attempting to delete an Allergen.

For reference here is the relevant client-side code:

const Allergen = ({ ..., removeAllergen }) => {
  const onDelete = () => {
    bootbox.confirm(`Are you sure that you wish to delete allergen '${allergen.name}'?`,
      (result) => {
        if (!result) return;
        removeAllergen({ id: allergen._id }).catch((methodError) => {
          toastr.error('An error occurred when attempting to delete the allergen');
          console.error('Error:', methodError);
        });
      },
    );
  };

  ...
};

const removeAllergen = gql`
  mutation removeAllergen($id: String!) {
    removeAllergen(id: $id)
  }
`;

const AllergenContainer = compose(
  graphql(removeAllergen, {
    props({ mutate }) {
      return {
        removeAllergen({ id }) {
          return mutate({
            variables: { id },
          });
        },
      };
    },
  }),
)(Allergen);

export default AllergenContainer;

and the server-side mutation:

export const schema = [`
  type Allergen {
    _id: String!
    createdAt: Date
    updatedAt: Date
    site: Site!
    siteId: String!
    name: String!
  }
`];

export const mutations = `
  # Deletes the specified allergen
  removeAllergen(id: String!): String
`;

export const mutationResolvers = {
  removeAllergen(root, { id }, context) {
    if (!context.user) throw new Meteor.Error('allergens.removeAllergen.login', 'Must be logged in.');

    const allergen = Allergens.findOne({ _id: id });
    if (!allergen) throw new Meteor.Error('allergens.removeAllergen.notFound', 'The specified allergen does not exist');
    userIsOwner(allergen, context.user);

    // Remove the allergen from the database and return the id of the removed document
    const docsRemoved = Allergens.remove({ _id: id });
    return docsRemoved === 1 ? id : null;
  },
};