Try to show more relevant exception messages when failing to restore a backup

app/src/main/java/eu/kanade/tachiyomi/data/backup/AbstractBackupRestoreValidator.kt

@@ -14,3 +14,5 @@ abstract class AbstractBackupRestoreValidator {
 
     data class Results(val missingSources: List<String>, val missingTrackers: List<String>)
 }
+
+class ValidatorParseException(e: Exception) : RuntimeException(e)

app/src/main/java/eu/kanade/tachiyomi/data/backup/full/FullBackupRestoreValidator.kt

@@ -4,12 +4,14 @@ import android.content.Context
 import android.net.Uri
 import eu.kanade.tachiyomi.R
 import eu.kanade.tachiyomi.data.backup.AbstractBackupRestoreValidator
+import eu.kanade.tachiyomi.data.backup.ValidatorParseException
 import eu.kanade.tachiyomi.data.backup.full.models.BackupSerializer
 import okio.buffer
 import okio.gzip
 import okio.source
 
 class FullBackupRestoreValidator : AbstractBackupRestoreValidator() {
+
     /**
      * Checks for critical backup file data.
      *
@@ -19,14 +21,20 @@ class FullBackupRestoreValidator : AbstractBackupRestoreValidator() {
     override fun validate(context: Context, uri: Uri): Results {
         val backupManager = FullBackupManager(context)
 
-        val backupString = context.contentResolver.openInputStream(uri)!!.source().gzip().buffer().use { it.readByteArray() }
-        val backup = backupManager.parser.decodeFromByteArray(BackupSerializer, backupString)
+        val backup = try {
+            val backupString =
+                context.contentResolver.openInputStream(uri)!!.source().gzip().buffer()
+                    .use { it.readByteArray() }
+            backupManager.parser.decodeFromByteArray(BackupSerializer, backupString)
+        } catch (e: Exception) {
+            throw ValidatorParseException(e)
+        }
 
         if (backup.backupManga.isEmpty()) {
             throw Exception(context.getString(R.string.invalid_backup_file_missing_manga))
         }
 
-        val sources = backup.backupSources.map { it.sourceId to it.name }.toMap()
+        val sources = backup.backupSources.associate { it.sourceId to it.name }
         val missingSources = sources
             .filter { sourceManager.get(it.key) == null }
             .values

app/src/main/java/eu/kanade/tachiyomi/data/backup/legacy/LegacyBackupRestoreValidator.kt

@@ -4,10 +4,12 @@ import android.content.Context
 import android.net.Uri
 import eu.kanade.tachiyomi.R
 import eu.kanade.tachiyomi.data.backup.AbstractBackupRestoreValidator
+import eu.kanade.tachiyomi.data.backup.ValidatorParseException
 import eu.kanade.tachiyomi.data.backup.legacy.models.Backup
 import kotlinx.serialization.json.decodeFromStream
 
 class LegacyBackupRestoreValidator : AbstractBackupRestoreValidator() {
+
     /**
      * Checks for critical backup file data.
      *
@@ -17,9 +19,13 @@ class LegacyBackupRestoreValidator : AbstractBackupRestoreValidator() {
     override fun validate(context: Context, uri: Uri): Results {
         val backupManager = LegacyBackupManager(context)
 
-        val backup = backupManager.parser.decodeFromStream<Backup>(
-            context.contentResolver.openInputStream(uri)!!
-        )
+        val backup = try {
+            backupManager.parser.decodeFromStream<Backup>(
+                context.contentResolver.openInputStream(uri)!!
+            )
+        } catch (e: Exception) {
+            throw ValidatorParseException(e)
+        }
 
         if (backup.version == null) {
             throw Exception(context.getString(R.string.invalid_backup_file_missing_data))
@@ -51,12 +57,10 @@ class LegacyBackupRestoreValidator : AbstractBackupRestoreValidator() {
 
     companion object {
         fun getSourceMapping(extensionsMapping: List<String>): Map<Long, String> {
-            return extensionsMapping
-                .map {
-                    val items = it.split(":")
-                    items[0].toLong() to items[1]
-                }
-                .toMap()
+            return extensionsMapping.associate {
+                val items = it.split(":")
+                items[0].toLong() to items[1]
+            }
         }
     }
 }

app/src/main/java/eu/kanade/tachiyomi/ui/setting/SettingsBackupController.kt

@@ -20,6 +20,7 @@ import eu.kanade.tachiyomi.data.backup.BackupConst
 import eu.kanade.tachiyomi.data.backup.BackupCreateService
 import eu.kanade.tachiyomi.data.backup.BackupCreatorJob
 import eu.kanade.tachiyomi.data.backup.BackupRestoreService
+import eu.kanade.tachiyomi.data.backup.ValidatorParseException
 import eu.kanade.tachiyomi.data.backup.full.FullBackupRestoreValidator
 import eu.kanade.tachiyomi.data.backup.full.models.BackupFull
 import eu.kanade.tachiyomi.data.backup.legacy.LegacyBackupRestoreValidator
@@ -262,12 +263,12 @@ class SettingsBackupController : SettingsController() {
 
             return try {
                 var type = BackupConst.BACKUP_TYPE_FULL
-                val results = runCatching {
+                val results = try {
                     FullBackupRestoreValidator().validate(activity, uri)
-                }.recoverCatching {
+                } catch (_: ValidatorParseException) {
                     type = BackupConst.BACKUP_TYPE_LEGACY
                     LegacyBackupRestoreValidator().validate(activity, uri)
-                }.getOrThrow()
+                }
 
                 var message = if (type == BackupConst.BACKUP_TYPE_FULL) {
                     activity.getString(R.string.backup_restore_content_full)