[libcalamares] Reduce indentation-depth in apply() through early-return

src/libcalamares/modulesystem/Config.cpp

@@ -94,16 +94,25 @@ Config::ApplyPresets::apply( const char* fieldName )
     if ( !prop.isValid() )
     {
         cWarning() << "Applying invalid property" << fieldName;
+        return *this;
     }
-    else
-    {
+
     const QString key( fieldName );
-        if ( !key.isEmpty() && m_c.d->m_presets->find( key ).isValid() )
+    if ( key.isEmpty() )
+    {
+        cWarning() << "Applying empty field";
+        return *this;
+    }
+
+    if ( m_c.d->m_presets->find( key ).isValid() )
     {
         cWarning() << "Applying duplicate property" << fieldName;
+        return *this;
     }
-        else if ( !key.isEmpty() && m_map.contains( key ) )
+
+    if ( m_map.contains( key ) )
     {
+        // Key has an explicit setting
         QVariantMap m = CalamaresUtils::getSubMap( m_map, key, m_bogus );
         QVariant value = m[ "value" ];
         bool editable = CalamaresUtils::getBool( m, "editable", true );
@@ -114,7 +123,6 @@ Config::ApplyPresets::apply( const char* fieldName )
         }
         m_c.d->m_presets->append( PresetField { key, value, editable } );
     }
-    }
     return *this;
 }