fix: reinstate undefined; remove checks

services/offline/src/lib/__tests__/use-online-status-message.test.tsx

@@ -16,7 +16,7 @@ describe('useOnlineStatusMessage', () => {
             wrapper,
         })
 
-        expect(result.current.onlineStatusMessage).toBeNull()
+        expect(result.current.onlineStatusMessage).toBeUndefined()
 
         act(() => {
             result.current.setOnlineStatusMessage('8 offline events')

services/offline/src/lib/online-status-message.tsx

@@ -4,7 +4,8 @@ type SetOnlineStatusMessage = (message: ReactNode) => void
 
 // 'get' and 'set' contexts are separated so 'setter' consumers that don't
 // actually need the value don't have to rerender when the value changes:
-const OnlineStatusMessageValueContext = React.createContext<ReactNode>(null)
+const OnlineStatusMessageValueContext =
+    React.createContext<ReactNode>(undefined)
 const SetOnlineStatusMessageContext =
     React.createContext<SetOnlineStatusMessage>(() => undefined)
 
@@ -13,8 +14,7 @@ export const OnlineStatusMessageProvider = ({
 }: {
     children: ReactNode
 }): ReactElement => {
-    const [onlineStatusMessage, setOnlineStatusMessage] =
-        useState<ReactNode>(null) // note: not undefined
+    const [onlineStatusMessage, setOnlineStatusMessage] = useState<ReactNode>() // note: not undefined
 
     return (
         <OnlineStatusMessageValueContext.Provider value={onlineStatusMessage}>
@@ -28,28 +28,11 @@ export const OnlineStatusMessageProvider = ({
 }
 
 export const useOnlineStatusMessageValue = () => {
-    const onlineStatusMessage = useContext(OnlineStatusMessageValueContext)
-
-    // note: value is initialized to `null` in provider, not undefined
-    if (onlineStatusMessage === undefined) {
-        throw new Error(
-            'useOnlineStatusMessageValue must be used within an OnlineStatusMessageProvider'
-        )
-    }
-
-    return onlineStatusMessage
+    return useContext(OnlineStatusMessageValueContext)
 }
 
 export const useSetOnlineStatusMessage = () => {
-    const setOnlineStatusMessage = useContext(SetOnlineStatusMessageContext)
-
-    if (setOnlineStatusMessage === undefined) {
-        throw new Error(
-            'useSetOnlineStatusMessage must be used within an OnlineStatusMessageProvider'
-        )
-    }
-
-    return setOnlineStatusMessage
+    return useContext(SetOnlineStatusMessageContext)
 }
 
 // combination of both getter and setter (also provides backward compatability)