Handle throwable with null message in REPL

[XomaDev]

https://github.com/mit-cml/appinventor-sources/blob/master/appinventor/buildserver/src/com/google/appinventor/buildserver/resources/runtime.scm#L419

Companion crashes where it fails to handle throwable with null error message, while this does not happen if the throwable has an empty or non-null string.

This happened at

• Fixes crash in a companion when a throwable is thrown with a null error message (runtime.scm)
• Use newer API for AlertDialog.setButton()
• Also change classes referencing RuntimeErrorAlert.alert()

[AppInventorWorkerBee]

Can one of the admins verify this patch?

[ewpatton]

@AppInventorWorkerBee ok to test

[ewpatton]

@XomaDev Note that because this affects companion behavior I have updated the base branch to ucr.

[ewpatton]

Is there an AIA file that will demonstrate the issue?

[jisqyv]

Using a newer API requires testing on older versions of Android that we still support.

[jisqyv]

I just checked, and the use of a different API for setButton should be fine (as of API level 3).

[XomaDev]

Is there an AIA file that will demonstrate the issue?

CompanionCrash.aia.zip

@SimpleFunction(description = "Does a crash")
public void Crash() throws Exception {
  throw new Exception();
}

[XomaDev]

So now

• When non-REPL: dialog is shown
• When REPL and toastAllowed: Toast+Report