Fix database issues

Fix some problems where PlaybackStateDatabase wouldn't downgrade [Problem when hopping between dev builds with db changes] and with assertBackgroundThread being public.

app/build.gradle

@@ -9,8 +9,8 @@ android {
 
     defaultConfig {
         applicationId "org.oxycblt.auxio"
-        versionName "1.4.0"
-        versionCode 6
+        versionName "1.3.3"
+        versionCode 5
 
         minSdkVersion 21
         targetSdkVersion 30

app/src/main/java/org/oxycblt/auxio/database/BlacklistDatabase.kt

@@ -24,8 +24,7 @@ class BlacklistDatabase(context: Context) : SQLiteOpenHelper(context, DB_NAME, n
     }
 
     override fun onDowngrade(db: SQLiteDatabase, oldVersion: Int, newVersion: Int) {
-        db.execSQL("DROP TABLE IF EXISTS $TABLE_NAME")
-        onCreate(db)
+        onUpgrade(db, newVersion, oldVersion)
     }
 
     /**

app/src/main/java/org/oxycblt/auxio/database/DatabaseUtils.kt

@@ -2,6 +2,7 @@ package org.oxycblt.auxio.database
 
 import android.database.Cursor
 import android.database.sqlite.SQLiteDatabase
+import android.database.sqlite.SQLiteOpenHelper
 import android.os.Looper
 
 /**
@@ -14,8 +15,8 @@ fun <R> SQLiteDatabase.queryAll(tableName: String, block: (Cursor) -> R) =
 /**
  * Assert that we are on a background thread.
  */
-fun assertBackgroundThread() {
-    if (Looper.myLooper() == Looper.getMainLooper()) {
-        error("Not on a background thread.")
+fun SQLiteOpenHelper.assertBackgroundThread() {
+    check(Looper.myLooper() != Looper.getMainLooper()) {
+        "Database operations must be ran on a background thread."
     }
 }

app/src/main/java/org/oxycblt/auxio/database/PlaybackStateDatabase.kt

@@ -30,6 +30,10 @@ class PlaybackStateDatabase(context: Context) :
         }
     }
 
+    override fun onDowngrade(db: SQLiteDatabase, oldVersion: Int, newVersion: Int) {
+        onUpgrade(db, newVersion, oldVersion)
+    }
+
     // --- DATABASE CONSTRUCTION FUNCTIONS ---
 
     /**