[packagechooser] Massage API

- use updateGlobalStorage() for both single-selection and
  model-based approaches, although the model-based one
  needs extra parameters.
- complain about inconsistent settings and API calls (e.g.
  setting a model and single-selection at the same time)

src/modules/packagechooser/Config.cpp

@@ -98,10 +98,13 @@ Config::introductionPackage() const
 void
 Config::updateGlobalStorage( const QStringList& selected ) const
 {
+    if ( m_packageChoice.has_value() )
+    {
+        cWarning() << "Inconsistent package choices -- both model and single-selection QML";
+    }
     if ( m_method == PackageChooserMethod::Legacy )
     {
         QString value = selected.join( ',' );
-        // QString value = ( m_pkgc );
         Calamares::JobQueue::instance()->globalStorage()->insert( m_id, value );
         cDebug() << m_id << "selected" << value;
     }
@@ -118,6 +121,36 @@ Config::updateGlobalStorage( const QStringList& selected ) const
     }
 }
 
+void
+Config::updateGlobalStorage() const
+{
+    if ( m_model->packageCount() > 0 )
+    {
+        cWarning() << "Inconsistent package choices -- both model and single-selection QML";
+    }
+    if ( m_method == PackageChooserMethod::Legacy )
+    {
+        auto* gs = Calamares::JobQueue::instance()->globalStorage();
+        if ( m_packageChoice.has_value() )
+        {
+            gs->insert( m_id, m_packageChoice.value() );
+        }
+        else
+        {
+            gs->remove( m_id );
+        }
+    }
+    else if ( m_method == PackageChooserMethod::Packages )
+    {
+        cWarning() << "Unsupported single-selection packagechooser method 'Packages'";
+    }
+    else
+    {
+        cWarning() << "Unknown packagechooser method" << smash( m_method );
+    }
+}
+
+
 void
 Config::setPackageChoice( const QString& packageChoice )
 {
@@ -252,5 +285,9 @@ Config::setConfigurationMap( const QVariantMap& configurationMap )
     else
     {
         setPackageChoice( CalamaresUtils::getString( configurationMap, "packageChoice" ) );
+        if ( m_method != PackageChooserMethod::Legacy )
+        {
+            cWarning() << "Single-selection QML module must use 'Legacy' method.";
+        }
     }
 }

src/modules/packagechooser/Config.h

@@ -85,8 +85,13 @@ public:
      * (and only) the packages in @p selected as selected.
      */
     void updateGlobalStorage( const QStringList& selected ) const;
-    /// As updateGlobalStorage() with an empty selection list
+    /** @brief Write selection to global storage
-    void fillGSSecondaryConfiguration() const { updateGlobalStorage( QStringList() ); }
+     *
+     * Updates the GS keys for this packagechooser, marking **only**
+     * the package choice as selected. This assumes that the single-
+     * selection QML code is in use.
+     */
+    void updateGlobalStorage() const;
 
     QString packageChoice() const { return m_packageChoice.value_or( QString() ); }
     void setPackageChoice( const QString& packageChoice );

src/modules/packagechooserq/PackageChooserQmlViewStep.cpp

@@ -74,7 +74,7 @@ PackageChooserQmlViewStep::jobs() const
 void
 PackageChooserQmlViewStep::onLeave()
 {
-    m_config->fillGSSecondaryConfiguration();
+    m_config->updateGlobalStorage();
 }
 
 void