#2902: Throw BusinessError on runBrick if tab is closed or has no access

src/background/executor.ts

@@ -28,13 +28,36 @@ import { runBrick } from "@/contentScript/messenger/api";
 import { Target } from "@/types";
 import { RemoteExecutionError } from "@/blocks/errors";
 import pDefer from "p-defer";
+import { canAccessTab } from "webext-tools";
+import { onTabClose } from "@/chrome";
 
 type TabId = number;
 
+// Used to determine which promise was resolved in a race
+const TYPE_WAS_CLOSED = Symbol("Tab was closed");
+
 const tabToOpener = new Map<TabId, TabId>();
 const tabToTarget = new Map<TabId, TabId>();
 // TODO: One tab could have multiple targets, but `tabToTarget` currenly only supports one at a time
 
+async function safelyRunBrick({ tabId }: { tabId: number }, request: RunBlock) {
+  if (!(await canAccessTab(tabId))) {
+    throw new BusinessError("PixieBrix doesn't have access to the tab");
+  }
+
+  const result = await Promise.race([
+    // If https://github.com/pixiebrix/webext-messenger/issues/67 is resolved, we don't need the listener
+    onTabClose(tabId).then(() => TYPE_WAS_CLOSED),
+    runBrick({ tabId }, request),
+  ]);
+
+  if (result === TYPE_WAS_CLOSED) {
+    throw new BusinessError("The tab was closed");
+  }
+
+  return result;
+}
+
 export async function waitForTargetByUrl(url: string): Promise<Target> {
   const { promise, resolve } = pDefer<Target>();
 
@@ -65,7 +88,7 @@ export async function requestRunInOpener(
     tabId: tabToOpener.get(sourceTabId),
   };
   const subRequest = { ...request, sourceTabId };
-  return runBrick(opener, subRequest);
+  return safelyRunBrick(opener, subRequest);
 }
 
 export async function requestRunInBroadcast(
@@ -87,7 +110,7 @@ export async function requestRunInBroadcast(
     }
 
     try {
-      const response = runBrick({ tabId: tab.id }, subRequest);
+      const response = safelyRunBrick({ tabId: tab.id }, subRequest);
       fulfilled.set(tab.id, await response);
     } catch (error) {
       rejected.set(tab.id, error);
@@ -113,7 +136,7 @@ export async function requestRunInTarget(
   }
 
   const subRequest = { ...request, sourceTabId };
-  return runBrick({ tabId: target }, subRequest);
+  return safelyRunBrick({ tabId: target }, subRequest);
 }
 
 export async function openTab(

src/chrome.ts

@@ -138,3 +138,16 @@ export async function setReduxStorage<T extends JsonValue = JsonValue>(
 ): Promise<void> {
   await browser.storage.local.set({ [storageKey]: JSON.stringify(value) });
 }
+
+export async function onTabClose(watchedTabId: number): Promise<void> {
+  await new Promise<void>((resolve) => {
+    const listener = (closedTabId: number) => {
+      if (closedTabId === watchedTabId) {
+        resolve();
+        browser.tabs.onRemoved.removeListener(listener);
+      }
+    };
+
+    browser.tabs.onRemoved.addListener(listener);
+  });
+}

src/errors.ts

@@ -174,9 +174,11 @@ export class ContextError extends Error {
   }
 }
 
+export const NO_TARGET_FOUND_CONNECTION_ERROR =
+  "Could not establish connection. Receiving end does not exist.";
 /** Browser Messenger API error message patterns */
 export const CONNECTION_ERROR_MESSAGES = [
-  "Could not establish connection. Receiving end does not exist.",
+  NO_TARGET_FOUND_CONNECTION_ERROR,
   "Extension context invalidated.",
 ];