NullPointerException: org.wordpress.aztec.spans.AztecHeadingSpan in chooseHeight

[sentry-io]

Sentry Issue: JETPACK-ANDROID-XQ

NullPointerException: None
    at org.wordpress.aztec.spans.AztecHeadingSpan.chooseHeight(AztecHeadingSpan.kt:131)
    at android.text.StaticLayout.out(StaticLayout.java:953)
    at android.text.StaticLayout.generate(StaticLayout.java:863)
    at android.text.DynamicLayout.reflow(DynamicLayout.java:612)
    at android.text.DynamicLayout.generate(DynamicLayout.java:479)
...
(26 additional frame(s) were not displayed)

[SiobhyB]

The first instance of this crash was seen in 20.5 (released on August 22nd, 2022). There were some height-related changes in Aztec around that time in wordpress-mobile/AztecEditor-Android#998 and wordpress-mobile/AztecEditor-Android#992. cc: @khaykov on the off-chance you may have an idea of what's causing this (I know Vojta's on leave).

The failure appears to happen at the chooseHeight function here:

https://github.com/wordpress-mobile/AztecEditor-Android/blob/b1f600a9ef80c7333ba190646db25899b633e793/aztec/src/main/kotlin/org/wordpress/aztec/spans/AztecHeadingSpan.kt#L122-L162

I've, unfortunately, been unable to reproduce as of yet. I've made a few different attempts to update settings in a headings block.

Adding this to Maintenance Week Issue Board - React Native for us to potentially dig deeper into during a maintenance week.

[khaykov]

@SiobhyB I checked Sentry and looks like we don't have this issue in Day One, where we use Aztec heavily. But we are not using it in React Native wrapper :) Looking at the code, I don't see any place where NPE can occur, unless some of the parameters coming into chooseHeight are null.

[sentry-io]

Sentry issue: WORDPRESS-ANDROID-2QDJ

[SiobhyB]

Sharing some findings from looking into this issue so far this week:

• The first instance of this crash in the Jetpack app was 20.5, but the first instance in the WordPress app was 19.2.
• Font size and line-height support was added for headings in 19.2 in [Mobile] - Enable font size and line height support and addresses Android issues WordPress/gutenberg#38205. As part of that, a change was made to the AztecHeadingSpan class in Heading Span - Reset previous font metrics if the font spacing changes AztecEditor-Android#952. It seems like any of these changes may have contributed to the crash.
• From a sample of 20 events, I noticed the following commonalities:
  • Mostly happens on pages, though I also saw a couple of cases of this happening with posts.
  • Mixture of site types, including self-hosted, Jetpack-connected, Atomic, and simple WordPress.com.
  • Many of the crash events are preceded by warnings that indicate some issues with performance or network e.g. Timeout reached before response from requestGetHtml, NETWORK_CAPABILITIES_CHANGED, LOW_MEMORY, com.android.volley.ClientError.
  • Mainly happening with themes that don't support line-height or font size changes for headings. I also saw a few cases where users had very recently switched from themes that do support those settings (such as Twenty Twenty-Three) to themes that don't (like Hever).

I've emailed a few users directly to see if they may be willing to provide some insights on specific steps they took before the crash.

I'm a bit stumped on next steps, as I haven't been able to reproduce the crash. All the parameters coming into the chooseHeight are non-nullable, but maybe they're being set as null elsewhere in the code.