Write test `test failure case displays toast`

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https://github.com/google/ground-android/blob/6cb83adc8cc1132d4ff11b08fc080d499130ee2c/app/src/test/java/com/google/android/ground/ui/offlineareas/selector/OfflineAreaSelectorFragmentTest.kt#L129-L130

    viewModel.downloadProgress.removeObserver(observer)
  }

  // TODO: Write `test test failure case displays toast`
  // Issue URL: https://github.com/google/ground-android/issues/3038
}