Fix: Prevent attempting to access non-existent nodes

This is defensive code that protects against attempting to dereference
  nodes that are not present, preventing the python code from throwing an
  AttributeError.

src/Mod/Assembly/CommandInsertLink.py

@@ -141,6 +141,15 @@ class TaskAssemblyInsertLink(QtCore.QObject):
         for insertionItem in self.insertionStack:
             object = insertionItem["addedObject"]
             translation = insertionItem["translation"]
+
+            # Check if object.Name & object.LinkedObject.Name exists
+            if (
+                not hasattr(object, "Name")
+                or not hasattr(object, "LinkedObject")
+                or not hasattr(object.LinkedObject, "Name")
+            ):
+                continue
+
             commands = commands + (
                 f'item = assembly.newObject("App::Link", "{object.Name}")\n'
                 f'item.LinkedObject = App.ActiveDocument.getObject("{object.LinkedObject.Name}")\n'
@@ -149,7 +158,7 @@ class TaskAssemblyInsertLink(QtCore.QObject):
 
             if translation != App.Vector():
                 commands = commands + (
-                    f"item.Placement.base = App.Vector({translation.x}."
+                    f"item.Placement.base = App.Vector({translation.x},"
                     f"{translation.y},"
                     f"{translation.z})\n"
                 )