Time travel seems broken

[aspiers]

If I try to go back in time, the web page in questions goes blank (white) and I get errors like this:

Warning: Can't perform a React state update on an unmounted component. This is a no-op, but it indicates a memory leak in your application. To fix, cancel all subscriptions and asynchronous tasks in the componentWillUnmount method.
    at TransitionGroup (webpack://@my/app/../node_modules/react-transition-group/esm/TransitionGroup.js?:53:30)
    at span
    at eval (webpack://@my/app/../node_modules/@emotion/react/dist/emotion-element-1c22787f.browser.esm.js?:54:66)
    at TouchRipple (webpack://@my/app/../node_modules/@mui/material/ButtonBase/TouchRipple.js?:154:83)
    at button
    at eval (webpack://@my/app/../node_modules/@emotion/react/dist/emotion-element-1c22787f.browser.esm.js?:54:66)
    at ButtonBase (webpack://@my/app/../node_modules/@mui/material/ButtonBase/ButtonBase.js?:111:82)
    at eval (webpack://@my/app/../node_modules/@emotion/react/dist/emotion-element-1c22787f.browser.esm.js?:54:66)
    at Button (webpack://@my/app/../node_modules/@mui/material/Button/Button.js?:233:83)
    at div
    at div
    at div
    at div
    at CheckRegistration (webpack://@my/app/./src/components/CheckRegistration/index.tsx?:21:27)
    at div

It comes from timeJump.ts:16, which corresponds to the breakpointed line in this source fragment: