Fix IPC API losing custom fields when updating footprints

pcbnew/api/api_pcb_utils.cpp

@@ -30,6 +30,7 @@
 #include <pcb_reference_image.h>
 #include <pcb_shape.h>
 #include <pcb_track.h>
+#include <pcb_field.h>
 #include <pcb_text.h>
 #include <pcb_textbox.h>
 #include <zone.h>
@@ -60,6 +61,16 @@ std::unique_ptr<BOARD_ITEM> CreateItemForType( KICAD_T aType, BOARD_ITEM_CONTAIN
         return std::make_unique<PAD>( footprint );
     }
 
+    case PCB_FIELD_T:
+    {
+        FOOTPRINT* footprint = dynamic_cast<FOOTPRINT*>( aContainer );
+
+        if( !footprint )
+            return nullptr;
+
+        return std::make_unique<PCB_FIELD>( footprint, FIELD_T::USER );
+    }
+
     case PCB_FOOTPRINT_T:
     {
         BOARD* board = dynamic_cast<BOARD*>( aContainer );