Fix currentTransaction in references while using query

src/main/kotlin/nl/astraeus/persistence/Persistent.kt

@@ -16,7 +16,19 @@ class Persistent(
   val datastore: Datastore = Datastore(directory, indexes, enableOptimisticLocking)
 
   fun <T> query(block: Query.() -> T): T {
-    return block(Query(this))
+    var cleanup = false
+    if (transactions.get() == null) {
+      transactions.set(Transaction(this))
+      cleanup = true
+    }
+
+    try {
+      return block(Query(this))
+    } finally {
+      if (cleanup) {
+        transactions.remove()
+      }
+    }
   }
 
   fun transaction(block: Transaction.() -> Unit) {

src/main/kotlin/nl/astraeus/persistence/reference/Reference.kt

@@ -10,7 +10,8 @@ inline fun <reified T : Persistable> reference(
 ) = Reference(T::class.java, initialValue)
 
 inline fun <reified T : Persistable> nullableReference(
-) = NullableReference(T::class.java)
+  initialValue:T? = null
+) = NullableReference(T::class.java, initialValue)
 
 class Reference<S : Persistable>(
   val cls: Class<S>,
@@ -33,9 +34,10 @@ class Reference<S : Persistable>(
 }
 
 class NullableReference<S : Persistable>(
-  val cls: Class<S>
+  val cls: Class<S>,
+  initialValue: S? = null
 ) : Serializable {
-  var id: Long? = null
+  var id: Long? = initialValue?.id
 
   operator fun getValue(thisRef: Persistable, property: KProperty<*>): S? {
     return currentTransaction()?.find(cls.kotlin, id ?: 0L)