Fix50d

If I click on the total line then an exception is thrown:
```
 Exception in thread "JavaFX Application Thread" scala.MatchError: BalanceReportEntry(None,  -12785.90) (of class co.uproot.abandon.BalanceReportEntry)
[error] 	at co.uproot.abandon.BalanceReport$BalanceView$1$$anon$5$$anonfun$handle$1.apply(BalanceReport.scala:36)
[error] 	at co.uproot.abandon.BalanceReport$BalanceView$1$$anon$5$$anonfun$handle$1.apply(BalanceReport.scala:35)
[error] 	at scala.collection.Iterator$class.foreach(Iterator.scala:743)
[error] 	at scalafx.collections.ObservableBuffer$$anon$1.foreach(ObservableBuffer.scala:400)
[error] 	at scala.collection.IterableLike$class.foreach(IterableLike.scala:72)
[error] 	at scalafx.collections.ObservableBuffer.foreach(ObservableBuffer.scala:218)

```

You should handle the default case for this match.