The unit tests cannot run

[isJaakko]

When I run pnpm test, I get an error as follows:

Error: Can only pipe to one destination
    at ReadableState.pipe (/Users/Projects/fontmin/node_modules/.pnpm/streamx@2.23.0/node_modules/streamx/index.js:263:37)
    at Transform.pipe (/Users/Projects/fontmin/node_modules/.pnpm/streamx@2.23.0/node_modules/streamx/index.js:730:25)
    at recurse (/Users/Projects/fontmin/node_modules/.pnpm/stream-combiner@0.2.2/node_modules/stream-combiner/index.js:27:16)
    at recurse (/Users/Projects/fontmin/node_modules/.pnpm/stream-combiner@0.2.2/node_modules/stream-combiner/index.js:28:5)
    at module.exports (/Users/Projects/fontmin/node_modules/.pnpm/stream-combiner@0.2.2/node_modules/stream-combiner/index.js:31:3)
    at Fontmin.createStream (file:///Users/Projects/fontmin/index.js:151:12)
    at file:///Users/Projects/fontmin/index.js:119:27
    at new Promise (<anonymous>)
    at Fontmin.runAsync (file:///Users/Projects/fontmin/index.js:118:12)
    at Stream.next (file:///Users/Projects/fontmin/test/font.spec.js:81:17)
    at Stream.emit (node:events:517:28)
    at DestroyableTransform.reemit (/Users/Projects/fontmin/node_modules/.pnpm/duplexer@0.1.2/node_modules/duplexer/index.js:85:16)
    at DestroyableTransform.emit (node:events:529:35)
    at /Users/Projects/fontmin/node_modules/.pnpm/through2@2.0.5/node_modules/through2/through2.js:19:12
    at process.processTicksAndRejections (node:internal/process/task_queues:77:11)