Fix interesting empty node socket spawning bugs.

This fixes two bugs with empty node socket spawning:
- The first time an empty is spawned, the link is moved to the last
socket.
- Unlinking a socket in the middle of the group would cause that socket
to be the one that's empty. This isn't bad per-se, but with Responders
being ID-based, it could result in some confusion.

korman/nodes/node_core.py

@@ -300,10 +300,32 @@ class PlasmaNodeBase:
         """Ensures that sockets are linked appropriately and there are enough inputs"""
         input_defs, output_defs = self._socket_defs
         for defs, sockets in ((input_defs, self.inputs), (output_defs, self.outputs)):
-            done = set()
-
-            # Need to enumerate by hand because blendsucks has major (crashing) issues if we modify
-            # this swhizzle while stuff is going down.
+            self._update_extant_sockets(defs, sockets)
+            self._update_init_sockets(defs, sockets)
+
+    def _update_init_sockets(self, defs, sockets):
+        # Create any missing sockets and spawn any required empties.
+        for alias, options in defs.items():
+            working_sockets = [(i, socket) for i, socket in enumerate(sockets) if socket.alias == alias]
+            if not working_sockets:
+                self._spawn_socket(alias, options, sockets)
+            elif options.get("spawn_empty", False):
+                last_socket_id = next(reversed(working_sockets))[0]
+                for working_id, working_socket in working_sockets:
+                    if working_id == last_socket_id and working_socket.is_linked:
+                        new_socket_id = len(sockets)
+                        new_socket = self._spawn_socket(alias, options, sockets)
+                        desired_id = last_socket_id + 1
+                        if new_socket_id != desired_id:
+                            sockets.move(new_socket_id, desired_id)
+                    elif working_id < last_socket_id and not working_socket.is_linked:
+                        # Indices do not update until after the update() function finishes, so
+                        # no need to decrement last_socket_id
+                        sockets.remove(working_socket)
+
+    def _update_extant_sockets(self, defs, sockets):
+        # Manually enumerate the sockets that are present for their presence and for the
+        # validity of their links. Can't use a for because we will overrun and crash Blender.
         i = 0
         while i < len(sockets):
             socket = sockets[i]
@@ -366,27 +388,8 @@ class PlasmaNodeBase:
                                 pass
                             continue
 
-                # If this is a spawn empty socket, make sure we have exactly one empty socket
-                if options.get("spawn_empty", False) and not socket.alias in done:
-                    empty_sockets = [j for j in sockets if j.bl_idname == socket.bl_idname and not j.is_used]
-                    if not empty_sockets:
-                        idx = len(sockets)
-                        dbg = sockets.new(socket.bl_idname, socket.name, socket.alias)
-                        # don't even ask...
-                        new_idx = i + 2
-                        if idx != new_idx:
-                            sockets.move(idx, new_idx)
-                    else:
-                        while len(empty_sockets) > 1:
-                            sockets.remove(empty_sockets.pop())
-                done.add(socket.alias)
-
             i += 1
 
-            # Create any new sockets
-            for alias in (j for j in defs if j not in done):
-                self._spawn_socket(alias, defs[alias], sockets)
-
     def _whine(self, msg, *args):
         if args:
             msg = msg.format(*args)