Fix coverity uninitialized member warnings

Author: nyalldawson

src/app/qgsattributesformproperties.h

@@ -203,7 +203,7 @@ class APP_EXPORT QgsAttributesFormProperties : public QWidget, private Ui_QgsAtt
     void loadAttributeRelationEdit();
     void storeAttributeRelationEdit( );
 
-    QgsEditFormConfig::PythonInitCodeSource mInitCodeSource;
+    QgsEditFormConfig::PythonInitCodeSource mInitCodeSource = QgsEditFormConfig::CodeSourceNone;
     QString mInitFunction;
     QString mInitFilePath;
     QString mInitCode;
@@ -268,7 +268,7 @@ class DnDTree : public QTreeWidget
 
   private:
     QgsVectorLayer *mLayer = nullptr;
-    Type mType;
+    Type mType = DnDTree::Type::Drag;
 };
 
 

src/app/qgssourcefieldsproperties.h

@@ -85,7 +85,7 @@ class APP_EXPORT QgsSourceFieldsProperties : public QWidget, private Ui_QgsSourc
     };
 
   private:
-    Ui::QgsSourceFieldsProperties *ui;
+    Ui::QgsSourceFieldsProperties *ui = nullptr;
     void updateFieldRenamingStatus();
 
   signals:

src/gui/qgsattributeformrelationeditorwidget.h

@@ -45,8 +45,8 @@ class GUI_EXPORT QgsAttributeFormRelationEditorWidget : public QgsAttributeFormW
     virtual QString currentFilterExpression() const override;
 
   private:
-    QgsRelationAggregateSearchWidgetWrapper *mSearchWidget;
-    QgsRelationWidgetWrapper *mWrapper;
+    QgsRelationAggregateSearchWidgetWrapper *mSearchWidget = nullptr;
+    QgsRelationWidgetWrapper *mWrapper = nullptr;
 };
 
 #endif // QGSATTRIBUTEFORMRELATIONEDITORWIDGET_H