Error with a custom jsx-runtime

[drinking-code]

So, I've setup ts-jest like this:

"jest": {
    "resolver": "<rootDir>/custom-resolver.cjs",
    "extensionsToTreatAsEsm": [".ts", ".tsx"],
    "preset": "ts-jest/presets/js-with-ts-esm",
    "transform": {
        "^.+\\.(m|c)?(j|t)sx?$": [
            "ts-jest",
            {
                "useESM": true
            }
        ]
    }
}

with the custom-resolver.cjs just pointing src/jsx-runtime to the correct file (otherwise I'd get Cannot find module 'src/jsx-runtime' from ...):

const path = require('path')

module.exports = function (modulePath, options) {
    if (modulePath === 'src/jsx-runtime') {
        return path.resolve('../src/jsx-runtime.ts')
    }
    return options.defaultResolver(modulePath, options)
}

But with this setup I am getting an Error:

Must use import to load ES Module: [redacted]/src/jsx-runtime.ts
at Runtime.requireModule (node_modules/jest-runtime/build/index.js:791:21)

How do I get rid of this error? / Is there a way to use my custom jsx-runtime in testing with ts-jest?