Fix SB.view nil access and GroupField child registration

1. Fix crash at editor.lua:154 - check SB.view exists before accessing
   - During View:init(), SB.view hasn't been assigned yet
   - Editors are created before SB.view is set in widget.lua

2. Fix GroupField child field registration logic
   - Changed from checking SB.view.useRmlUi (which is nil during init)
   - Now checks: if field.fields exists AND field.Added doesn't exist
   - RmlUi GroupFields: have .fields, no .Added → register children here
   - Chili GroupFields: have .fields, have .Added → register in Added()
   - This works regardless of when SB.view is set

Fixes:
- "attempt to index field 'view' (a nil value)" crash
- "Attempted to set non-existent field: sunDirX" (and other GroupField children)

Author: claude

scen_edit/view/editor.lua

@@ -151,7 +151,7 @@ function Editor:Finalize(children, opts)
             classname = opts.classname,
         }
         -- Only set main panel in Chili mode
-        if not SB.view.useRmlUi and SB.view.tabbedWindow then
+        if SB.view and not SB.view.useRmlUi and SB.view.tabbedWindow then
             SB.view.tabbedWindow:SetMainPanel(self.window)
         end
     else
@@ -363,8 +363,10 @@ function Editor:AddField(field)
     end
     self:_AddField(field)
 
-    -- In RmlUi mode, register child fields of GroupField
-    if SB.view and SB.view.useRmlUi and field.fields then
+    -- Register child fields of GroupField
+    -- RmlUi GroupFields have .fields but no .Added method (handled here)
+    -- Chili GroupFields have .fields and .Added method (handled in Added())
+    if field.fields and not field.Added then
         for _, childField in ipairs(field.fields) do
             if childField.name then
                 self:_AddField(childField)