Crash report: `Error: Unsupported chain ID`

URL

https://app.uniswap.org/#/swap?chain=

swap state

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

Error

Error: Unsupported chain ID

Stacktrace

Error: Unsupported chain ID
    at n.get (https://app.uniswap.org/static/js/main.8c9f966b.chunk.js:1:535062)
    at https://app.uniswap.org/static/js/main.8c9f966b.chunk.js:1:632780
    at sf (https://app.uniswap.org/static/js/2.365a8d52.chunk.js:2:2442916)
    at Ya (https://app.uniswap.org/static/js/2.365a8d52.chunk.js:2:2495216)
    at Cs (https://app.uniswap.org/static/js/2.365a8d52.chunk.js:2:2482457)
    at Ts (https://app.uniswap.org/static/js/2.365a8d52.chunk.js:2:2482385)
    at Os (https://app.uniswap.org/static/js/2.365a8d52.chunk.js:2:2482248)
    at ws (https://app.uniswap.org/static/js/2.365a8d52.chunk.js:2:2479214)
    at https://app.uniswap.org/static/js/2.365a8d52.chunk.js:2:2428708
    at t.unstable_runWithPriority (https://app.uniswap.org/static/js/2.365a8d52.chunk.js:2:2505945)

Device data

{
  "ua": "Mozilla/5.0 (Linux; Android 10; Android SDK built for x86 Build/OSM1.180201.023) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/77.0.3865.92 Mobile Safari/537.36",
  "browser": {
    "name": "Chrome",
    "version": "77.0.3865.92",
    "major": "77"
  },
  "engine": {
    "name": "Blink",
    "version": "77.0.3865.92"
  },
  "os": {
    "name": "Android",
    "version": "10"
  },
  "device": {
    "model": "Android SDK built for x86",
    "type": "mobile"
  },
  "cpu": {}
}

Reproduce https://app.uniswap.org/#/swap?chain= with the reported swap state and inspect the stack trace locations in main.8c9f966b.chunk.js and 2.365a8d52.chunk.js. Trace how the empty chain value reaches the unsupported-chain error, then verify the URL no longer crashes the interface.