React error for useEffect Hook conditional call when there is no such conditional call

React is complaining about code below, saying it useEffect is being called conditionally:

import React, { useEffect } from "react";
import ReactDOM from "react-dom";

function App() {
  const documentCounts = {};
  const invertedIndexes = {};

  for (const term of []) {
    if (!invertedIndexes[term]) continue;
    // The offending code is the loop below
    for (const arr of invertedIndexes[term]) {
      const documentIndex = arr[0];
      if (!documentCounts[documentIndex]) documentCounts[documentIndex] = 1;
      else ++documentCounts[documentIndex];
    }
  }

  useEffect(() => {});

  return (
    <div className="App">
      <h1>Hello World</h1>
    </div>
  );
}

const rootElement = document.getElementById("root");
ReactDOM.render(<App />, rootElement);

React Hook "useEffect" is called conditionally. React Hooks must be called in the exact same order in every component render. Did you accidentally call a React Hook after an early return? react-hooks/rules-of-hooks

But to me it seems like there is no conditional call to useEffect – the loop just modifies local variables. Does anyone happen to know what the problem here is?

(the pointless variables are what I boiled down my original code down to to try to pinpoint the issue)

Sandbox:
https://codesandbox.io/s/friendly-diffie-z7edc