Fix export crashes in Android 9

[emanuele-f]

This fixes the following crashes in Android 9 (honor 9 lite):

Startup crash due to null mCalendars.get(i).mName:

2022-05-14 19:16:40.330 16853-16960/org.sufficientlysecure.ical E/AndroidRuntime: FATAL EXCEPTION: Thread-3
    Process: org.sufficientlysecure.ical, PID: 16853
    java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.lang.String.contentEquals(java.lang.CharSequence)' on a null object reference
        at org.sufficientlysecure.ical.ui.MainActivity.initialiseCalendars(MainActivity.java:359)
        at org.sufficientlysecure.ical.ui.MainActivity.access$1500(MainActivity.java:81)
        at org.sufficientlysecure.ical.ui.MainActivity$9.run(MainActivity.java:442)
        at java.lang.Thread.run(Thread.java:784)
2022-05-14 19:16:40.355 16853-16960/org.sufficientlysecure.ical I/Process: Sending signal. PID: 16853 SIG: 9

Export crash due to null cursor returned due to unsupported columns:

2022-05-14 19:18:25.015 17114-17181/org.sufficientlysecure.ical E/ICS_RunnableWithProgress: An exception occurred
    java.lang.NullPointerException: Attempt to invoke interface method 'int android.database.Cursor.getCount()' on a null object reference
        at org.sufficientlysecure.ical.SaveCalendar.getEvents(SaveCalendar.java:255)
        at org.sufficientlysecure.ical.SaveCalendar.run(SaveCalendar.java:193)
        at org.sufficientlysecure.ical.ui.dialogs.RunnableWithProgress$1.run(RunnableWithProgress.java:44)
        at java.lang.Thread.run(Thread.java:784)

Export working correctly after the fixes

[fhaftmann]

Hi,

thanks for diving into this.

After having a look at it, I have the following remarks:

• Since the changes address different breakdown reasons, the commit should be split into two.

• I am not sure whether the second change is accurate. My impression is that the guard mCalendars.get(i).mName != null should just go the corresponding clause, hence sth. like (calendarName == null || (mCalendars.get(i).mName != null && mCalendars.get(i).mName.contentEquals(calendarName))) which in turn could maybe be compactified to (calendarName == null || calendarName.contentEquals(mCalendars.get(i).mName). Or is there something I miss?

• Concerning the first change, a space should go between if and (. I would also prefer if the generous catch-all could be avoided totally, e. g. the documentation of the .query method suggests that catching OperationCanceledException is enough, but that is maybe too risky.

[emanuele-f]

Please refactor as you wish. The traces above should be enough to pinpoint the issues. The query method returns null on my phone as the the stack trace shows.

[Martin-Laclaustra]

I experienced "Export crash due to null cursor returned due to unsupported columns" problem, and I confirm that this pull request solves it.

A year has gone by since the problem and solution were spotted.

@fhaftmann or any other maintainer. Given that the changes are only a few lines, could you please consider just creating your own commits, separated as deemed necessary, with the repository-compatible formatting and with a more limited exception catching, and creating a new release?

That way this app will continue alive and working for the community.

Thanks for the app, and the attention.

[sbaum2s]

This app is no longer in google play store. So its basically dead. I would like to add it again since the license here allows everything as far as i got it. I came across this issue because i want to port my phone´s data to a new one and wondered why this app cant be installed on other phones anymore. Its not available anymore.