- Using 'Scripting'
The tabs that existed before your extension was installed did not have the content script running on them. When you tried to send a message to such a tab, the receiving end (i.e., the content script) did not exist, and hence you encountered the error. To address this issue, before sending a message using chrome.tabs.sendMessage, use chrome.scripting.executeScript to inject the content script into the target tab. Once the injection is successful, then you can proceed to send your message. I used 'scripting' to solve these problems.

- Using 'storage'
Even if this extension is closed and reopened, storage must be used to remember the id of the tab whose scroll position will be synchronized.

- Using 'tabs'
It is used to get the information of the currently open tabs to select the tabs to synchronize the scroll position.

- 'host'
This extension does not bound to any specific host. Therefore, it should be able to run a content script to synchronize the scroll position