Staged migration from material ui 4 to MUI5

I am working on a project with lots of traffic ion regards to commits. My thinking was the best way to go about this migration would be to start with this guide https://mui.com/guides/migration-v4/ and basically install the new packages, run code mods, then have the two version material ui 4 and MUI5 living side by side while components were refactored one by one. This would require keeping out uses of createStyles and makeStyles. However I am running into a problem.

In the code below, theme is undefined:

const useStyles = makeStyles<Theme>(
  (theme) =>
    createStyles({
      ...
      drawer: {
        zIndex: theme.zIndex.drawer,
      ...

Is there a way to have material ui 4 and MUI5 living together temporarily? If so, why would theme be undefined in this case?