[libcalamaresui] Set config object earlier

- The config context object should be set earlier, otherwise
   QML code will try binding to a non-existent config already
 - Document that QMLViewStep::setConfigurationMap() parent implementation
   should be called **last**, at the end of the subclass implementation.

src/libcalamaresui/viewpages/QmlViewStep.cpp

@@ -210,11 +210,6 @@ QmlViewStep::loadComplete()
             // It is marked \internal in the Qt sources, but does exactly
             // what is needed: sets up visual parent by replacing the root
             // item, and handling resizes.
-            QObject* config = this->getConfig();
-            if ( config )
-            {
-                m_qmlWidget->engine()->rootContext()->setContextProperty( "config", config );
-            }
             m_qmlWidget->setContent( QUrl( m_qmlFileName ), m_qmlComponent, m_qmlObject );
             showQml();
         }
@@ -320,6 +315,12 @@ QmlViewStep::setConfigurationMap( const QVariantMap& configurationMap )
     {
         m_qmlFileName = searchQmlFile( m_searchMethod, qmlFile, m_name );
 
+        QObject* config = this->getConfig();
+        if ( config )
+        {
+            m_qmlWidget->engine()->rootContext()->setContextProperty( "config", config );
+        }
+
         cDebug() << "QmlViewStep" << moduleInstanceKey() << "loading" << m_qmlFileName;
         m_qmlComponent = new QQmlComponent(
             m_qmlWidget->engine(), QUrl( m_qmlFileName ), QQmlComponent::CompilationMode::Asynchronous );

src/libcalamaresui/viewpages/QmlViewStep.h

@@ -73,7 +73,7 @@ public:
     /// @brief QML widgets don't produce jobs by default
     virtual JobList jobs() const override;
 
-    /// @brief Configure search paths; subclasses should call this as well
+    /// @brief Configure search paths; subclasses should call this at the **end** of their own implementation
     virtual void setConfigurationMap( const QVariantMap& configurationMap ) override;
 
 protected:

src/modules/notesqml/NotesQmlViewStep.cpp

@@ -36,9 +36,7 @@ NotesQmlViewStep::prettyName() const
 
 void
 NotesQmlViewStep::setConfigurationMap( const QVariantMap& configurationMap )
-{ 
+{
-    Calamares::QmlViewStep::setConfigurationMap( configurationMap ); // call parent implementation
-    
     bool qmlLabel_ok = false;
     auto qmlLabel = CalamaresUtils::getSubMap( configurationMap, "qmlLabel", qmlLabel_ok );
 
@@ -46,7 +44,8 @@ NotesQmlViewStep::setConfigurationMap( const QVariantMap& configurationMap )
     {
         m_notesName = new CalamaresUtils::Locale::TranslatedString( qmlLabel, "notes" );
     }
-    
+
+    Calamares::QmlViewStep::setConfigurationMap( configurationMap ); // call parent implementation last
 }
 
 CALAMARES_PLUGIN_FACTORY_DEFINITION( NotesQmlViewStepFactory, registerPlugin< NotesQmlViewStep >(); )

src/modules/welcomeq/WelcomeQmlViewStep.cpp

@@ -90,7 +90,6 @@ jobOrBrandingSetting( Calamares::Branding::StringEntry e, const QVariantMap& map
 void
 WelcomeQmlViewStep::setConfigurationMap( const QVariantMap& configurationMap )
 {
-    QmlViewStep::setConfigurationMap( configurationMap );
     using Calamares::Branding;
 
     m_config.setHelpUrl( jobOrBrandingSetting( Branding::SupportUrl, configurationMap, "showSupportUrl" ) );
@@ -146,6 +145,8 @@ WelcomeQmlViewStep::setConfigurationMap( const QVariantMap& configurationMap )
             // TODO: figure out where to set this: Config?
         }
     }
+
+    QmlViewStep::setConfigurationMap( configurationMap );  // call parent implementation last
 }
 
 Calamares::RequirementsList