Crash when opening Naming Numbers revision card in Place Values

[BenHenning]

Stack trace:

    java.lang.RuntimeException: Failed to call observer method
        at androidx.lifecycle.ClassesInfoCache$MethodReference.invokeCallback(ClassesInfoCache.java:226)
        at androidx.lifecycle.ClassesInfoCache$CallbackInfo.invokeMethodsForEvent(ClassesInfoCache.java:194)
        at androidx.lifecycle.ClassesInfoCache$CallbackInfo.invokeCallbacks(ClassesInfoCache.java:185)
        at androidx.lifecycle.ReflectiveGenericLifecycleObserver.onStateChanged(ReflectiveGenericLifecycleObserver.java:37)
        at androidx.lifecycle.LifecycleRegistry$ObserverWithState.dispatchEvent(LifecycleRegistry.java:361)
        at androidx.lifecycle.LifecycleRegistry.forwardPass(LifecycleRegistry.java:300)
        at androidx.lifecycle.LifecycleRegistry.sync(LifecycleRegistry.java:339)
        at androidx.lifecycle.LifecycleRegistry.moveToState(LifecycleRegistry.java:145)
        at androidx.lifecycle.LifecycleRegistry.handleLifecycleEvent(LifecycleRegistry.java:131)
        at androidx.fragment.app.Fragment.performStart(Fragment.java:2732)
        at androidx.fragment.app.FragmentStateManager.start(FragmentStateManager.java:331)
        at androidx.fragment.app.FragmentManager.moveToState(FragmentManager.java:1239)
        at androidx.fragment.app.FragmentManager.moveToState(FragmentManager.java:1398)
        at androidx.fragment.app.FragmentManager.moveFragmentToExpectedState(FragmentManager.java:1476)
        at androidx.fragment.app.FragmentManager.moveToState(FragmentManager.java:1541)
        at androidx.fragment.app.FragmentManager.dispatchStateChange(FragmentManager.java:2858)
        at androidx.fragment.app.FragmentManager.dispatchStart(FragmentManager.java:2818)
        at androidx.fragment.app.FragmentController.dispatchStart(FragmentController.java:258)
        at androidx.fragment.app.FragmentActivity.onStart(FragmentActivity.java:550)
        at androidx.appcompat.app.AppCompatActivity.onStart(AppCompatActivity.java:201)
        at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1432)
        at android.app.Activity.performStart(Activity.java:7825)
        at android.app.ActivityThread.handleStartActivity(ActivityThread.java:3294)
        at android.app.servertransaction.TransactionExecutor.performLifecycleSequence(TransactionExecutor.java:221)
        at android.app.servertransaction.TransactionExecutor.cycleToPath(TransactionExecutor.java:201)
        at android.app.servertransaction.TransactionExecutor.executeLifecycleState(TransactionExecutor.java:173)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:97)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2016)
        at android.os.Handler.dispatchMessage(Handler.java:107)
        at android.os.Looper.loop(Looper.java:214)
        at android.app.ActivityThread.main(ActivityThread.java:7356)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)
     Caused by: java.lang.IndexOutOfBoundsException: setSpan (1966 ... 1965) has end before start
        at android.text.SpannableStringBuilder.checkRange(SpannableStringBuilder.java:1318)
        at android.text.SpannableStringBuilder.setSpan(SpannableStringBuilder.java:684)
        at android.text.SpannableStringBuilder.setSpan(SpannableStringBuilder.java:676)
        at android.text.HtmlToSpannedConverter.convert(Html.java:774)
        at android.text.Html.fromHtml(Html.java:243)
        at androidx.core.text.HtmlCompat.fromHtml(HtmlCompat.java:162)
        at org.oppia.util.parser.CustomHtmlContentHandler$Companion.fromHtml(CustomHtmlContentHandler.kt:146)
        at org.oppia.util.parser.HtmlParser.parseOppiaHtml(HtmlParser.kt:77)
        at org.oppia.util.parser.HtmlParser.parseOppiaHtml$default(HtmlParser.kt:48)
        at org.oppia.app.topic.revisioncard.RevisionCardViewModel.processExplanationResult(RevisionCardViewModel.kt:80)
        at org.oppia.app.topic.revisioncard.RevisionCardViewModel.access$processExplanationResult(RevisionCardViewModel.kt:22)

Seems related to the recent bullet span work.