export function assertIdValue(idValue: IdValue) {
  if (!isIdValue(idValue)) {
    throw new Error(`Encountered a sub-selection on the query, but the store doesn't have \
an object reference. This should never happen during normal use unless you have custom code \
that is directly manipulating the store; please file an issue.`);
  }
}

function assertSelectionSetForIdValue(
  field: FieldNode,
  value: any,
) {
  if (!field.selectionSet && isIdValue(value)) {
    throw new InvariantError(
      `Missing selection set for object of type ${
        value.typename
      } returned for query field ${field.name.value}`
    );
  }
}

    return value.map((item, i) => {
      // By default the previous result for this item will be in the same array position as this
      // item.
      let itemPreviousResult = previousResult && previousResult[i];

      // If the item is an id value, we should check to see if there is a previous result for this
      // specific id. If there is, that will be the value for `itemPreviousResult`.
      if (isIdValue(item)) {
        itemPreviousResult =
          idToPreviousResult.get(item.id) || itemPreviousResult;
      }

      return addPreviousResultToIdValues(item, itemPreviousResult);
    });