Crash report: `Error: invalid decimal value (argument="value", value="66,9", code=INVALID_ARGUMENT, version=bignumber/5.6.2)`

URL

https://app.uniswap.org/#/swap

swap state

{
  "INPUT": {
    "currencyId": "ETH"
  },
  "OUTPUT": {
    "currencyId": null
  },
  "typedValue": "",
  "independentField": "INPUT",
  "recipient": null
}

Error

Error: invalid decimal value (argument="value", value="66,9", code=INVALID_ARGUMENT, version=bignumber/5.6.2)

Stacktrace

Error: invalid decimal value (argument="value", value="66,9", code=INVALID_ARGUMENT, version=bignumber/5.6.2)
    at e.value (https://app.uniswap.org/static/js/4.ef60cbe2.chunk.js:2:102827)
    at e.value (https://app.uniswap.org/static/js/4.ef60cbe2.chunk.js:2:102971)
    at e.value (https://app.uniswap.org/static/js/4.ef60cbe2.chunk.js:2:103050)
    at v (https://app.uniswap.org/static/js/4.ef60cbe2.chunk.js:2:2048905)
    at s (https://app.uniswap.org/static/js/4.ef60cbe2.chunk.js:2:474654)
    at c (https://app.uniswap.org/static/js/4.ef60cbe2.chunk.js:2:474721)
    at p (https://app.uniswap.org/static/js/main.3752d112.chunk.js:1:717860)
    at https://app.uniswap.org/static/js/main.3752d112.chunk.js:1:721273
    at Array.map (<anonymous>)
    at https://app.uniswap.org/static/js/main.3752d112.chunk.js:1:721243

Device data

{
  "ua": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/107.0.0.0 Safari/537.36",
  "browser": {
    "name": "Chrome",
    "version": "107.0.0.0",
    "major": "107"
  },
  "engine": {
    "name": "Blink",
    "version": "107.0.0.0"
  },
  "os": {
    "name": "Mac OS",
    "version": "10.15.7"
  },
  "device": {},
  "cpu": {}
}

The report points to https://app.uniswap.org/#/swap and a deployed JavaScript stacktrace, but names no repository file or test. Reproduce the reported swap state and invalid decimal value, then trace the stack into the source; done means the swap page no longer crashes for this case.