fix types error

src/components/Popups/Popups.tsx

@@ -53,7 +53,7 @@ const Popups: React.FC = () => {
     egl_failure: false,
     notification_activated: false,
   })
-  const [previousEndDate, setPreviousEndDate] = useState<string>()
+  const [previousEndDate, setPreviousEndDate] = useState<string | null>()
   const [customPopup, setCustomPopup] = useState<ICustomPopup>({
     popupEnabled: false,
     title: '',
@@ -147,7 +147,7 @@ const Popups: React.FC = () => {
           setCustomPopup({
             ...customPopupData,
           })
-          setPreviousEndDate(customPopupData.endDate || undefined)
+          setPreviousEndDate(customPopupData.endDate ?? undefined)
         }
       }
       setIsLoading(false)

src/models/customPopup.model.ts

@@ -3,7 +3,7 @@ import { durationType } from './durationOptions.model'
 export interface ICustomPopup {
   description: string
   popupEnabled: boolean
-  endDate: string
+  endDate: string | null
   title: string
 }