EntityStore: let totalCount be undefined, don't try to set it from the local count

app/soapbox/entity-store/hooks/useEntities.ts

@@ -4,6 +4,7 @@ import z from 'zod';
 import { getNextLink, getPrevLink } from 'soapbox/api';
 import { useApi, useAppDispatch, useAppSelector, useGetState } from 'soapbox/hooks';
 import { filteredArray } from 'soapbox/schemas/utils';
+import { realNumberSchema } from 'soapbox/utils/numbers';
 
 import { entitiesFetchFail, entitiesFetchRequest, entitiesFetchSuccess, invalidateEntityList } from '../actions';
 
@@ -63,12 +64,12 @@ function useEntities<TEntity extends Entity>(
       const response = await api.get(url);
       const schema = opts.schema || z.custom<TEntity>();
       const entities = filteredArray(schema).parse(response.data);
-      const numItems = (selectList(getState(), path)?.ids.size || 0) + entities.length;
+      const parsedCount = realNumberSchema.safeParse(response.headers['x-total-count']);
 
       dispatch(entitiesFetchSuccess(entities, entityType, listKey, {
         next: getNextLink(response),
         prev: getPrevLink(response),
-        totalCount: Number(response.headers['x-total-count'] ?? numItems) || 0,
+        totalCount: parsedCount.success ? parsedCount.data : undefined,
         fetching: false,
         fetched: true,
         error: null,

app/soapbox/entity-store/reducer.ts

@@ -71,11 +71,14 @@ const deleteEntities = (
         for (const list of Object.values(cache.lists)) {
           if (list) {
             list.ids.delete(id);
+
+            if (typeof list.state.totalCount === 'number') {
               list.state.totalCount--;
             }
           }
         }
       }
+    }
 
     draft[entityType] = cache;
   });
@@ -94,8 +97,11 @@ const dismissEntities = (
     if (list) {
       for (const id of ids) {
         list.ids.delete(id);
+
+        if (typeof list.state.totalCount === 'number') {
           list.state.totalCount--;
         }
+      }
 
       draft[entityType] = cache;
     }

app/soapbox/entity-store/types.ts

@@ -24,7 +24,7 @@ interface EntityListState {
   /** Previous URL for pagination, if any. */
   prev: string | undefined
   /** Total number of items according to the API. */
-  totalCount: number
+  totalCount: number | undefined
   /** Error returned from the API, if any. */
   error: any
   /** Whether data has already been fetched */

app/soapbox/entity-store/utils.ts

@@ -13,8 +13,10 @@ const updateList = (list: EntityList, entities: Entity[]): EntityList => {
   const newIds = entities.map(entity => entity.id);
   const ids = new Set([...Array.from(list.ids), ...newIds]);
 
+  if (typeof list.state.totalCount === 'number') {
     const sizeDiff = ids.size - list.ids.size;
     list.state.totalCount += sizeDiff;
+  }
 
   return {
     ...list,

app/soapbox/utils/numbers.tsx

@@ -1,9 +1,13 @@
 import React from 'react';
 import { FormattedNumber } from 'react-intl';
+import { z } from 'zod';
 
 /** Check if a value is REALLY a number. */
 export const isNumber = (value: unknown): value is number => typeof value === 'number' && !isNaN(value);
 
+/** The input is a number and is not NaN. */
+export const realNumberSchema = z.coerce.number().refine(n => !isNaN(n));
+
 export const secondsToDays = (seconds: number) => Math.floor(seconds / (3600 * 24));
 
 const roundDown = (num: number) => {