Address NullPointerException crash in AztecHeadingSpan

[SiobhyB]

Fixes #18657

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Related PRs

• Gutenberg: [RNMobile] Address NullPointerException crash in AztecHeadingSpan WordPress/gutenberg#56757
• Gutenberg Mobile: [RNMobile] Address NullPointerException crash in AztecHeadingSpan gutenberg-mobile#6435
• Aztec Android: Address NullPointerException crash in AztecHeadingSpan AztecEditor-Android#1071

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To Test

• Install the app using the installable build from this PR.
• Navigate to the post editor.
• Add some heading blocks and ensure there are no unexpected side effects when performing tasks. Example tasks to test include splitting the block, applying new font sizes and line heights, etc.

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Regression Notes

1. Potential unintended areas of impact

   • Although the changes shouldn't create unwanted side effects, we're still changing the chooseHeight override. As described here, that function defines the height for a given element. As such, changes to that override may impact how heights are calculated for heading blocks.

2. What I did to test those areas of impact (or what existing automated tests I relied on)

   • Manually tested the heading block via the installable build.

3. What automated tests I added (or what prevented me from doing so)

   • As we're only adding safety checks to the code and the testing is visual, there aren't any obvious ways to implement automated tests.

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PR Submission Checklist:

• I have completed the Regression Notes.
• I have considered adding accessibility improvements for my changes.
• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.

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[wpmobilebot]

📲 You can test the changes from this Pull Request in Jetpack by scanning the QR code below to install the corresponding build.

	App Name	Jetpack
	Flavor	Jalapeno
	Build Type	Debug
	Version	pr19724-d814948
	Commit	d814948
	Direct Download	jetpack-prototype-build-pr19724-d814948.apk

Note: Google Login is not supported on these builds.

[wpmobilebot]

📲 You can test the changes from this Pull Request in WordPress by scanning the QR code below to install the corresponding build.

	App Name	WordPress
	Flavor	Jalapeno
	Build Type	Debug
	Version	pr19724-d814948
	Commit	d814948
	Direct Download	wordpress-prototype-build-pr19724-d814948.apk

Note: Google Login is not supported on these builds.

[fluiddot]

Approved via wordpress-mobile/AztecEditor-Android#1071 (review).

NOTE: If we plan to incorporate this fix in the ongoing beta version 23.8, we should consider pointing this PR to the branch release/23.8.

[wpmobilebot]

Found 1 violations:

The PR caused the following dependency changes:

 \--- project :libs:editor
-     +--- org.wordpress:aztec:{strictly v1.8.0} -> v1.8.0
+     +--- org.wordpress:aztec:{strictly v1.9.0} -> v1.9.0
-     +--- org.wordpress.aztec:wordpress-shortcodes:{strictly v1.8.0} -> v1.8.0
-     |    +--- org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.6.10 -> 1.9.10 (*)
-     |    +--- org.wordpress:aztec:v1.8.0 (*)
-     |    \--- androidx.appcompat:appcompat:1.0.0 -> 1.6.1 (*)
+     +--- org.wordpress.aztec:wordpress-shortcodes:{strictly v1.9.0} -> v1.9.0
+     |    +--- org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.6.10 -> 1.9.10 (*)
+     |    +--- org.wordpress:aztec:v1.9.0 (*)
+     |    \--- androidx.appcompat:appcompat:1.0.0 -> 1.6.1 (*)
-     +--- org.wordpress.aztec:wordpress-comments:{strictly v1.8.0} -> v1.8.0
-     |    +--- org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.6.10 -> 1.9.10 (*)
-     |    +--- org.wordpress:aztec:v1.8.0 (*)
-     |    +--- androidx.legacy:legacy-support-v4:1.0.0 (*)
-     |    \--- com.google.android.material:material:1.0.0 -> 1.9.0 (*)
+     +--- org.wordpress.aztec:wordpress-comments:{strictly v1.9.0} -> v1.9.0
+     |    +--- org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.6.10 -> 1.9.10 (*)
+     |    +--- org.wordpress:aztec:v1.9.0 (*)
+     |    +--- androidx.legacy:legacy-support-v4:1.0.0 (*)
+     |    \--- com.google.android.material:material:1.0.0 -> 1.9.0 (*)
      \--- org.wordpress-mobile.gutenberg-mobile:react-native-gutenberg-bridge:v1.109.1
           \--- org.wordpress-mobile.gutenberg-mobile:react-native-aztec:v1.109.1
-               +--- org.wordpress:aztec:v1.8.0 (*)
+               +--- org.wordpress:aztec:v1.8.0 -> v1.9.0 (*)
-               +--- org.wordpress.aztec:wordpress-shortcodes:v1.8.0 (*)
+               +--- org.wordpress.aztec:wordpress-shortcodes:v1.8.0 -> v1.9.0 (*)
-               +--- org.wordpress.aztec:wordpress-comments:v1.8.0 (*)
+               +--- org.wordpress.aztec:wordpress-comments:v1.8.0 -> v1.9.0 (*)
                \--- org.wordpress.aztec:glide-loader:v1.8.0
-                    \--- org.wordpress:aztec:v1.8.0 (*)
+                    \--- org.wordpress:aztec:v1.8.0 -> v1.9.0 (*)

Please review and act accordingly

[peril-wordpress-mobile]

	Warnings
⚠️	This PR is assigned to a milestone which is closing in less than 4 days Please, make sure to get it merged by then or assign it to a later expiring milestone

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