Fix deleteDatabase blocking due to open connections

- Automatically close database connections on delete
- Handle "blocked" event in deleteDatabase

core/src/jsMain/kotlin/Database.kt

@@ -46,15 +46,22 @@ public suspend fun openDatabase(
 public suspend fun deleteDatabase(name: String) {
     val factory = checkNotNull(window.indexedDB) { "Your browser doesn't support IndexedDB." }
     val request = factory.deleteDatabase(name)
-    request.onNextEvent("success", "error") { event ->
+    request.onNextEvent("success", "error", "blocked") { event ->
         when (event.type) {
-            "error" -> throw ErrorEventException(event)
+            "error", "blocked" -> throw ErrorEventException(event)
             else -> null
         }
     }
 }
 
-public class Database internal constructor(internal val database: IDBDatabase) {
+public class Database internal constructor(database: IDBDatabase) {
+    private var _database: IDBDatabase? = database
+    internal val database: IDBDatabase
+        get() = _database ?: throw Exception("Database closed")
+    init {
+        database.addEventListener("versionchange", { close() })
+        database.addEventListener("close", { close() })
+    }
 
     /**
      * Inside the [action] block, you must not call any `suspend` functions except for:
@@ -102,6 +109,7 @@ public class Database internal constructor(internal val database: IDBDatabase) {
 
     public fun close() {
         database.close()
+        _database = null
     }
 }