QmlDesigner: Fix some Qml null warnings

Remove some warnings that appear on launch and shut down

Change-Id: I0eb58eadd9e975f0cfc7ec74636f540c26042589
Reviewed-by: Miikka Heikkinen <miikka.heikkinen@qt.io>
Reviewed-by: Thomas Hartmann <thomas.hartmann@qt.io>

share/qtcreator/qmldesigner/propertyEditorQmlSources/imports/HelperWidgets/ColorLogic.qml

@@ -9,20 +9,11 @@ QtObject {
 
     property variant backendValue
     property color textColor: StudioTheme.Values.themeTextColor
-    property variant valueFromBackend: root.backendValue === undefined ? 0 : root.backendValue.value
+    property variant valueFromBackend: root.backendValue?.value ?? 0
     property bool baseStateFlag: isBaseState
-    property bool isInModel: {
-        if (root.backendValue !== undefined && root.backendValue.isInModel !== undefined)
-            return root.backendValue.isInModel
+    property bool isInModel: root.backendValue?.isInModel ?? false
+    property bool isInSubState: root.backendValue?.isInSubState ?? false
 
-        return false
-    }
-    property bool isInSubState: {
-        if (root.backendValue !== undefined && root.backendValue.isInSubState !== undefined)
-            return root.backendValue.isInSubState
-
-        return false
-    }
     property bool highlight: root.textColor === root.__changedTextColor
     property bool errorState: false
 
@@ -38,7 +29,7 @@ QtObject {
     onErrorStateChanged: root.evaluate()
 
     function evaluate() {
-        if (root.backendValue === undefined)
+        if (!root.backendValue)
             return
 
         if (root.errorState) {
@@ -47,15 +38,11 @@ QtObject {
         }
 
         if (root.baseStateFlag) {
-            if (root.backendValue.isInModel)
-                root.textColor = root.__changedTextColor
-            else
-                root.textColor = root.__defaultTextColor
+            root.textColor = root.backendValue.isInModel ? root.__changedTextColor
+                                                         : root.__defaultTextColor
         } else {
-            if (root.backendValue.isInSubState)
-                root.textColor = StudioTheme.Values.themeChangedStateText
-            else
-                root.textColor = root.__defaultTextColor
+            root.textColor = root.backendValue.isInSubState ? StudioTheme.Values.themeChangedStateText
+                                                            : root.__defaultTextColor
         }
     }
 }

share/qtcreator/qmldesigner/propertyEditorQmlSources/imports/HelperWidgets/ComboBox.qml

@@ -19,7 +19,7 @@ StudioControls.ComboBox {
 
     onModelChanged: colorLogic.invalidate()
 
-    hasActiveDrag: comboBox.backendValue !== undefined && comboBox.backendValue.hasActiveDrag
+    hasActiveDrag: comboBox.backendValue?.hasActiveDrag ?? false
 
     // This is available in all editors.
 
@@ -120,7 +120,7 @@ StudioControls.ComboBox {
                     break
                 case ComboBox.ValueType.Enum:
                 default:
-                    if (comboBox.backendValue === undefined)
+                    if (!comboBox.backendValue)
                         break
 
                     var enumString = comboBox.backendValue.enumeration

share/qtcreator/qmldesigner/propertyEditorQmlSources/imports/HelperWidgets/ExtendedFunctionLogic.qml

@@ -11,18 +11,8 @@ Item {
     id: extendedFunctionButton
 
     property variant backendValue
-    property bool isBoundBackend: {
-        if (backendValue !== undefined && backendValue.isBound !== undefined)
-            return backendValue.isBound
-
-        return false
-    }
-    property string backendExpression: {
-        if (backendValue !== undefined && backendValue.expression !== undefined)
-            return backendValue.expression
-
-        return ""
-    }
+    property bool isBoundBackend: backendValue?.isBound ?? false
+    property string backendExpression: backendValue?.expression ?? ""
 
     property string glyph: StudioTheme.Constants.actionIcon
     property string color: StudioTheme.Values.themeTextColor
@@ -38,7 +28,7 @@ Item {
 
     function setIcon() {
         extendedFunctionButton.color = StudioTheme.Values.themeTextColor
-        if (backendValue === undefined) {
+        if (!backendValue) {
             extendedFunctionButton.glyph = StudioTheme.Constants.actionIcon
         } else if (backendValue.isBound) {
             if (backendValue.isTranslated) {
@@ -49,12 +39,8 @@ Item {
                 extendedFunctionButton.color = StudioTheme.Values.themeInteraction
             }
         } else {
-            if (backendValue.complexNode !== undefined
-                    && backendValue.complexNode.exists) {
-
-            } else {
+            if (!backendValue.complexNode || !backendValue.complexNode.exists)
                 extendedFunctionButton.glyph = StudioTheme.Constants.actionIcon
-            }
         }
     }
 
@@ -77,8 +63,8 @@ Item {
                 id: menu
 
                 onAboutToShow: {
-                    exportMenuItem.checked = backendValue.hasPropertyAlias()
-                    exportMenuItem.enabled = !backendValue.isAttachedProperty()
+                    exportMenuItem.checked = backendValue?.hasPropertyAlias() ?? false
+                    exportMenuItem.enabled = !(backendValue?.isAttachedProperty() ?? false)
                     extendedFunctionButton.menuVisible = true
                 }
                 onAboutToHide: extendedFunctionButton.menuVisible = false

share/qtcreator/qmldesigner/propertyEditorQmlSources/imports/HelperWidgets/LineEdit.qml

@@ -111,8 +111,7 @@ StudioControls.TextField {
         lineEdit.__dirty = false
     }
 
-    property bool isTranslated: colorLogic.backendValue === undefined ? false
-                                                                      : colorLogic.backendValue.isTranslated
+    property bool isTranslated: colorLogic.backendValue?.isTranslated ?? false
 
     translationIndicator.onClicked: {
         if (lineEdit.translationIndicator.checked) {
@@ -124,19 +123,12 @@ StudioControls.TextField {
         colorLogic.evaluate()
     }
 
-    property variant backendValueValueInternal: lineEdit.backendValue === undefined ? 0
-                                                                                    : lineEdit.backendValue.value
+    property variant backendValueValueInternal: lineEdit.backendValue?.value ?? 0
     onBackendValueValueInternalChanged: {
-        if (lineEdit.backendValue === undefined)
-            lineEdit.translationIndicator.checked = false
-        else
-            lineEdit.translationIndicator.checked = lineEdit.backendValue.isTranslated
+        lineEdit.translationIndicator.checked = lineEdit.backendValue?.isTranslated ?? false
     }
 
     onIsTranslatedChanged: {
-        if (lineEdit.backendValue === undefined)
-            lineEdit.translationIndicator.checked = false
-        else
-            lineEdit.translationIndicator.checked = lineEdit.backendValue.isTranslated
+        lineEdit.translationIndicator.checked = lineEdit.backendValue?.isTranslated ?? false
     }
 }

share/qtcreator/qmldesigner/propertyEditorQmlSources/imports/HelperWidgets/SpinBox.qml

@@ -31,18 +31,18 @@ Item {
     }
 
     Component.onCompleted: {
-        spinBox.enabled = backendValue === undefined ? false : !isBlocked(backendValue.name)
+        spinBox.enabled = backendValue ? !isBlocked(backendValue.name) : false
     }
 
     Connections {
         target: modelNodeBackend
         function onSelectionChanged() {
-            spinBox.enabled = backendValue === undefined ? false : !isBlocked(backendValue.name)
+            spinBox.enabled = backendValue ? !isBlocked(backendValue.name) : false
         }
     }
 
     onBackendValueChanged: {
-        spinBox.enabled = backendValue === undefined ? false : !isBlocked(backendValue.name)
+        spinBox.enabled = backendValue ? !isBlocked(backendValue.name) : false
     }
 
     StudioControls.RealSpinBox {

share/qtcreator/qmldesigner/propertyEditorQmlSources/imports/HelperWidgets/UrlChooser.qml

@@ -88,7 +88,7 @@ Row {
         ToolTip {
             id: toolTip
             visible: comboBox.hover && toolTip.text !== ""
-            text: root.backendValue.valueToString
+            text: root.backendValue?.valueToString ?? ""
             delay: StudioTheme.Values.toolTipDelay
 
             background: Rectangle {