How do I approach solving this problem: Cannot access 'calculationEntry' before initialization?

I'm developing a large CRA single page app. It has been running fine for months, with the normal bugs that are normally fixable. A couple of weeks ago it failed by just hanging in the splash page with a spinning circle. No code was hit so no breakpoints worked. I did a lot of experimentation with the importing and exporting of all the files, thinking that was the root cause. Finally I thought to do a build and run that. That did get past the splash screen and generate an exception. The first was fixed, but now I get this Cannot access 'calculationEntry' before initialization error. I'm using VSCode and the launch.json configuration is:

  "name": "Chrome React",
  "type": "chrome",
  "request": "launch",
  "sourceMaps": true,
  "url": "http://localhost:3000",
  "webRoot": "${workspaceRoot}/src",
  "userDataDir": "${workspaceRoot}/.chrome",
  "sourceMapPathOverrides": {
    "webpack:///src/*": "${webRoot}/*"
  },
  "breakOnLoad": true

I can't show example code, the whole project compiles without error. The error occurs when I run with f5. This is what I get. The name 'calculationEntry' is a function, and I think that a function is initialized when declared. So why this error?

        "use strict";
    __webpack_require__.r(__webpack_exports__);
    /* WEBPACK VAR INJECTION */(function(__react_refresh_utils__, __react_refresh_error_overlay__) {/* harmony export (binding) */ __webpack_require__.d(__webpack_exports__, "calculationEntry", function() { return calculationEntry; });
                                                                                ^
    Exception has occurred: ReferenceError: Cannot access 'calculationEntry' before initialization
      at Module.calculationEntry (http://localhost:3000/static/js/main.chunk.js:5896:204)
        at Module.calculationEntry (http://localhost:3000/static/js/main.chunk.js:53960:169)
        at Object.registerExportsForReactRefresh (http://localhost:3000/static/js/vendors~main.chunk.js:995:38)
        at Module.<anonymous> (http://localhost:3000/static/js/main.chunk.js:54703:25)
        at Module../src/moduleNameSpace.js (http://localhost:3000/static/js/main.chunk.js:54775:30)
        at __webpack_require__ (http://localhost:3000/static/js/bundle.js:852:31)
        at fn (http://localhost:3000/static/js/bundle.js:151:20)
        at Module.<anonymous> (http://localhost:3000/static/js/main.chunk.js:5897:74)
        at Module../src/calculations/moduleCalc0.js (http://localhost:3000/static/js/main.chunk.js:6104:30)
        at __webpack_require__ (http://localhost:3000/static/js/bundle.js:852:31)
        at fn (http://localhost:3000/static/js/bundle.js:151:20)
        at Module.<anonymous> (http://localhost:3000/static/js/main.chunk.js:37915:84)
        at Module../src/components/Forecaster/index.js (http://localhost:3000/static/js/main.chunk.js:38243:30)
        at __webpack_require__ (http://localhost:3000/static/js/bundle.js:852:31)
        at fn (http://localhost:3000/static/js/bundle.js:151:20)
        at Module.<anonymous> (http://localhost:3000/static/js/main.chunk.js:47062:82)
        at Module../src/components/Root/Root.dev.js (http://localhost:3000/static/js/main.chunk.js:47396:30)
        at __webpack_require__ (http://localhost:3000/static/js/bundle.js:852:31)
        at fn (http://localhost:3000/static/js/bundle.js:151:20)
        at Object.<anonymous> (http://localhost:3000/static/js/main.chunk.js:47779:20)
        at Object../src/components/Root/index.js (http://localhost:3000/static/js/main.chunk.js:47855:30)
        at __webpack_require__ (http://localhost:3000/static/js/bundle.js:852:31)
        at fn (http://localhost:3000/static/js/bundle.js:151:20)
        at Module.<anonymous> (http://localhost:3000/static/js/main.chunk.js:51422:74)
        at Module../src/index.js (http://localhost:3000/static/js/main.chunk.js:51577:30)
        at __webpack_require__ (http://localhost:3000/static/js/bundle.js:852:31)
        at fn (http://localhost:3000/static/js/bundle.js:151:20)
        at Object.1 (http://localhost:3000/static/js/main.chunk.js:57861:18)
        at __webpack_require__ (http://localhost:3000/static/js/bundle.js:852:31)
        at checkDeferredModules (http://localhost:3000/static/js/bundle.js:46:23)
        at Array.webpackJsonpCallback [as push] (http://localhost:3000/static/js/bundle.js:33:19)
        at http://localhost:3000/static/js/main.chunk.js:1:79

I have a module doing all the imports and re-exporting all the named exports that I made to try preventing cyclic references, and I moved the location of the import of the module with the calculationEntry function, to see if it made a difference. It did not. So I need some help in how to use this debug dump to track down this TDZ exceptions problem.

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