refactor: AnkiDroidApp initialization error types

This code was converted from Java, and needs to be extended
 to handle other types of error for issue 13207

For this, a `sealed class` which contains each type of initialization error
 is a reusable abstraction

Related to issue 13207

Author: david-allison

AnkiDroid/src/main/java/com/ichi2/anki/AnkiDroidApp.kt

@@ -79,8 +79,8 @@ import java.util.Locale
 open class AnkiDroidApp :
     Application(),
     ChangeManager.Subscriber {
-    /** An exception if the WebView subsystem fails to load  */
-    private var webViewError: Throwable? = null
+    /** An exception if AnkiDroidApp fails to load  */
+    private var fatalInitializationError: FatalInitializationError? = null
 
     @LegacyNotifications("The widget triggers notifications by posting null to this, but we plan to stop relying on the widget")
     private val notifications = MutableLiveData<Void?>()
@@ -302,7 +302,7 @@ open class AnkiDroidApp :
             // 5794: Errors occur if the WebView fails to load
             // android.webkit.WebViewFactory.MissingWebViewPackageException.MissingWebViewPackageException
             // Error may be excessive, but I expect a UnsatisfiedLinkError to be possible here.
-            webViewError = e
+            fatalInitializationError = FatalInitializationError.WebViewError(e)
             sendExceptionReport(e, "setAcceptFileSchemeCookies")
             Timber.e(e, "setAcceptFileSchemeCookies")
             false
@@ -474,16 +474,24 @@ open class AnkiDroidApp :
                     else -> appResources.getString(R.string.link_manual)
                 }
 
-        fun webViewFailedToLoad(): Boolean = instance.webViewError != null
+        /** (optional) set if an unrecoverable error occurs during Application startup */
+        val fatalError: FatalInitializationError?
+            get() = instance.fatalInitializationError
+    }
+}
 
-        val webViewErrorMessage: String?
-            get() {
-                val error = instance.webViewError
-                if (error == null) {
-                    Timber.w("getWebViewExceptionMessage called without webViewFailedToLoad check")
-                    return null
-                }
-                return ExceptionUtil.getExceptionMessage(error)
+/**
+ * Types of unrecoverable errors which we want to inform the user of
+ */
+sealed class FatalInitializationError {
+    data class WebViewError(
+        val error: Throwable,
+    ) : FatalInitializationError()
+
+    /** Advanced/developer-facing string representing the error */
+    val errorDetail: String
+        get() =
+            when (this) {
+                is WebViewError -> ExceptionUtil.getExceptionMessage(error)
             }
-    }
 }

AnkiDroid/src/main/java/com/ichi2/anki/DeckPicker.kt

@@ -90,7 +90,6 @@ import com.ichi2.anki.InitialActivity.StartupFailure.DirectoryNotAccessible
 import com.ichi2.anki.InitialActivity.StartupFailure.DiskFull
 import com.ichi2.anki.InitialActivity.StartupFailure.FutureAnkidroidVersion
 import com.ichi2.anki.InitialActivity.StartupFailure.SDCardNotMounted
-import com.ichi2.anki.InitialActivity.StartupFailure.WebviewFailed
 import com.ichi2.anki.IntentHandler.Companion.intentToReviewDeckFromShortcuts
 import com.ichi2.anki.account.AccountActivity
 import com.ichi2.anki.analytics.UsageAnalytics
@@ -999,16 +998,10 @@ open class DeckPicker :
                 Timber.i("Displaying database locked error")
                 showDatabaseErrorDialog(DatabaseErrorDialogType.DIALOG_DB_LOCKED)
             }
-            is WebviewFailed ->
+            is StartupFailure.InitializationError ->
                 AlertDialog.Builder(this).show {
                     title(R.string.ankidroid_init_failed_webview_title)
-                    message(
-                        text =
-                            getString(
-                                R.string.ankidroid_init_failed_webview,
-                                AnkiDroidApp.webViewErrorMessage,
-                            ),
-                    )
+                    message(text = failure.toHumanReadableString(this@DeckPicker))
                     positiveButton(R.string.close) {
                         closeCollectionAndFinish()
                     }

AnkiDroid/src/main/java/com/ichi2/anki/InitialActivity.kt

@@ -48,9 +48,8 @@ object InitialActivity {
     /** Returns null on success  */
     @CheckResult
     fun getStartupFailureType(initializeAnkiDroidDirectory: () -> Boolean): StartupFailure? {
-        // A WebView failure means that we skip `AnkiDroidApp`, and therefore haven't loaded the collection
-        if (AnkiDroidApp.webViewFailedToLoad()) {
-            return StartupFailure.WebviewFailed
+        AnkiDroidApp.fatalError?.let {
+            return StartupFailure.InitializationError(it)
         }
 
         val failure =
@@ -150,7 +149,21 @@ object InitialActivity {
 
         data object DatabaseLocked : StartupFailure()
 
-        data object WebviewFailed : StartupFailure()
+        /**
+         * [AnkiDroidApp] encountered a fatal error
+         */
+        data class InitializationError(
+            val error: FatalInitializationError,
+        ) : StartupFailure() {
+            fun toHumanReadableString(context: Context): String =
+                when (error) {
+                    is FatalInitializationError.WebViewError ->
+                        context.getString(
+                            R.string.ankidroid_init_failed_webview,
+                            error.errorDetail,
+                        )
+                }
+        }
 
         data object DiskFull : StartupFailure()
     }