Improve Redux types part 4 (#26003)

* Fix return type of addUsersToChannel

* Fix type of TeamInviteWithError.error

* Change Constants.Integrations.PAGE_SIZE into a number"

webapp/platform/client/src/client4.ts

@@ -1535,7 +1535,7 @@ export default class Client4 {
     sendEmailGuestInvitesToChannelsGracefully = async (teamId: string, channelIds: string[], emails: string[], message: string) => {
         this.trackEvent('api', 'api_teams_invite_guests', {team_id: teamId, channel_ids: channelIds});
 
-        return this.doFetch<TeamInviteWithError>(
+        return this.doFetch<TeamInviteWithError[]>(
             `${this.getTeamRoute(teamId)}/invite-guests/email?graceful=true`,
             {method: 'post', body: JSON.stringify({emails, channels: channelIds, message})},
         );