Don't nullify cache (tldraw#5310)

accidentally introduced a couple of minor bugs by nullifying the cache,
so in this PR i make it so that the interval just starts and stops
rather than completely getting rid of the cache.

### Change type

- [x] `bugfix`

apps/dotcom/client/src/routes.tsx

@@ -17,7 +17,7 @@ const LoginRedirectPage = lazy(() => import('./components/LoginRedirectPage/Logi
 export const tlaOverrideFlag = 'tla-override-flag'
 export const tlaProbablyLoggedInFlag = 'tla-probably-logged-in-flag'
 
-const isOverrideFlagSet = !!getFromLocalStorage(tlaOverrideFlag) || navigator.webdriver
+export const isOverrideFlagSet = !!getFromLocalStorage(tlaOverrideFlag) || navigator.webdriver
 const isProbablyLoggedIn = !!getFromLocalStorage(tlaProbablyLoggedInFlag)
 
 export function SetPreviewFlag(props: PropsWithChildren) {

apps/dotcom/client/src/tla/components/TlaEditor/PreviewWelcomeDialog.tsx

@@ -13,6 +13,7 @@ import {
 	useEditor,
 	useValue,
 } from 'tldraw'
+import { isOverrideFlagSet } from '../../../routes'
 import { getScratchPersistenceKey } from '../../../utils/scratch-persistence-key'
 import { useApp } from '../../hooks/useAppState'
 import { useCurrentFileId } from '../../hooks/useCurrentFileId'
@@ -126,7 +127,7 @@ export function PreviewWelcomeDialog() {
 	)
 
 	useEffect(() => {
-		if (shouldShowWelcomeDialog) {
+		if (shouldShowWelcomeDialog && !isOverrideFlagSet) {
 			userHasSlurpableDocument().then((hasSlurpableDocument) => {
 				dialogs.addDialog({
 					id: dialogId,

apps/dotcom/sync-worker/src/TLUserDurableObject.ts

@@ -125,6 +125,7 @@ export class TLUserDurableObject extends DurableObject<Environment> {
 
 	private assertCache(): asserts this is { cache: UserDataSyncer } {
 		assert(this.cache, 'no cache')
+		this.cache.maybeStartInterval()
 	}
 
 	private readonly sockets = new Set<WebSocket>()
@@ -146,9 +147,7 @@ export class TLUserDurableObject extends DurableObject<Environment> {
 
 	maybeClose() {
 		if (this.sockets.size === 0) {
-			this.cache?.close()
-			this.cache = null
-			// db will time out after 10 seconds of inactivity so no need to close it manually
+			this.cache?.stopInterval()
 		}
 	}
 

apps/dotcom/sync-worker/src/UserDataSyncer.ts

@@ -117,7 +117,7 @@ export class UserDataSyncer {
 		}
 	}
 
-	interval
+	interval: NodeJS.Timeout | null = null
 
 	constructor(
 		private ctx: DurableObjectState,
@@ -131,12 +131,19 @@ export class UserDataSyncer {
 		this.sentry = createSentry(ctx, env)
 		this.replicator = getReplicator(env)
 		this.reboot(false)
+	}
 
-		this.interval = setInterval(() => this.__rebootIfMutationsNotCommitted(), 1000)
+	maybeStartInterval() {
+		if (!this.interval) {
+			this.interval = setInterval(() => this.__rebootIfMutationsNotCommitted(), 1000)
+		}
 	}
 
-	close() {
-		clearInterval(this.interval)
+	stopInterval() {
+		if (this.interval) {
+			clearInterval(this.interval)
+			this.interval = null
+		}
 	}
 
 	private queue = new ExecutionQueue()