Hovering unloaded tab causes console error

Steps to reproduce:

1. Visit en.wikipedia.org.
2. Open a new tab.
3. Right click the wikipedia tab and select "Unload Tab".
4. Hover the wikipedia tab.

Get the console error:

NS_ERROR_FAILURE: Component returned failure code: 0x80004005 (NS_ERROR_FAILURE) [nsISpeculativeConnect.speculativeConnect]
    prepareConnectionToHost resource:///modules/sessionstore/SessionStore.sys.mjs:5873
    speculativeConnectOnTabHover resource:///modules/sessionstore/SessionStore.sys.mjs:5896
    speculativeConnectOnTabHover resource:///modules/sessionstore/SessionStore.sys.mjs:666
    _mouseenter chrome://browser/content/tabbrowser/tab.js:633
    on_mouseover chrome://browser/content/tabbrowser/tab.js:415
    handleEvent chrome://global/content/customElements.js:459
SessionStore.sys.mjs:5877:17

Probably because we disable speculativeConnect somehow. I don't know if upstream has not taken a preference into account, or whether this is something one of our own patches broke.

NOTE: I believe that being able to manually unload a tab is a new feature for ESR 140. Although I think the unloading mechanism was still in place beforehand.