[netinstall] Edge cases of zero, or unset, groups urls

- consumers may wait for loadingDone(), so always emit that
  even if no URL list is set.

src/modules/netinstall/Config.cpp

@@ -136,27 +136,24 @@ Config::setConfigurationMap( const QVariantMap& configurationMap )
     // Lastly, load the groups data
     const QString key = QStringLiteral( "groupsUrl" );
     const auto& groupsUrlVariant = configurationMap.value( key );
+    m_queue = new LoaderQueue( this );
     if ( groupsUrlVariant.type() == QVariant::String )
     {
-        m_queue = new LoaderQueue( this );
         m_queue->append( SourceItem::makeSourceItem( groupsUrlVariant.toString(), configurationMap ) );
     }
     else if ( groupsUrlVariant.type() == QVariant::List )
     {
-        m_queue = new LoaderQueue( this );
         for ( const auto& s : groupsUrlVariant.toStringList() )
         {
             m_queue->append( SourceItem::makeSourceItem( s, configurationMap ) );
         }
     }
-    if ( m_queue && m_queue->count() > 0 )
-    {
-        cDebug() << "Loading netinstall from" << m_queue->count() << "alternate sources.";
+
     setStatus( required() ? Status::FailedNoData : Status::Ok );
+    cDebug() << "Loading netinstall from" << m_queue->count() << "alternate sources.";
     connect( m_queue, &LoaderQueue::done, this, &Config::loadingDone );
     m_queue->load();
 }
-}
 
 void
 Config::finalizeGlobalStorage( const Calamares::ModuleSystem::InstanceKey& key )

src/modules/netinstall/Tests.cpp

@@ -347,6 +347,7 @@ ItemTests::testUrlFallback_data()
     QTest::newRow( "error" ) << "1a-single-error.conf" << smash( S::FailedBadData ) << 0;
     QTest::newRow( "second" ) << "1b-single-small.conf" << smash( S::Ok ) << 2;
     QTest::newRow( "none" ) << "1c-none.conf" << smash( S::FailedNoData ) << 0;
+    QTest::newRow( "unset" ) << "1c-unset.conf" << smash( S::FailedNoData ) << 0;
 }
 
 void

src/modules/netinstall/tests/1c-unset.conf

@@ -0,0 +1,5 @@
+# SPDX-FileCopyrightText: no
+# SPDX-License-Identifier: CC0-1.0
+#
+---
+required: true