Fix some small bugs

Author: Hanseter

src/main/kotlin/com/github/hanseter/json/editor/JsonPropertiesEditor.kt

@@ -164,6 +164,7 @@ class JsonPropertiesEditor @JvmOverloads constructor(
     }
 
     fun removeObject(objId: String) {
+        treeTableView.selectionModel.clearSelection()
         (idsToPanes.remove(objId)?.treeItem)?.also {
             (treeTableView.root as FilterableTreeItem).remove(it)
         }
@@ -203,6 +204,7 @@ class JsonPropertiesEditor @JvmOverloads constructor(
     }
 
     fun clear() {
+        treeTableView.selectionModel.clearSelection()
         idsToPanes.clear()
         (treeTableView.root as FilterableTreeItem).clear()
         rebindValidProperty()
@@ -322,7 +324,7 @@ class JsonPropertiesEditor @JvmOverloads constructor(
                 createValidationMessage(
                     label,
                     treeItemData.validationMessage
-                )?.also(DECORATOR::applyValidationDecoration)
+                )?.also { Platform.runLater { DECORATOR.applyValidationDecoration(it) } }
             }
         }
 

src/main/kotlin/com/github/hanseter/json/editor/controls/MultiLineStringControl.kt

@@ -14,7 +14,7 @@ class MultiLineStringControl : ControlWithProperty<String?> {
         prefHeightProperty().bind(maxHeightProperty())
         minHeightProperty().bind(maxHeightProperty())
         textProperty().addListener { _, _, text ->
-            if ('\n' in text) {
+            if (text?.contains('\n') == true) {
                 maxHeight = 70.0
                 setHorizonzalScrollbarPolicy(ScrollPane.ScrollBarPolicy.AS_NEEDED)
             } else {

src/main/kotlin/com/github/hanseter/json/editor/ui/FilterableTreeItem.kt

@@ -46,7 +46,7 @@ class FilterableTreeItem<T>(value: T) : TreeItem<T>(value) {
     fun setFilter(filter: (T) -> Boolean) {
         filteredList.setPredicate { child ->
             child.setFilter(filter)
-            if (child.children.size > 0) {
+            if (child.children.isNotEmpty()) {
                 true
             } else {
                 filter(child.value)