cmd.get("enter", enter) AttributeError: 'str' object has no attribute 'get'

the code

from tmuxp.workspace.freezer import freeze
from tmuxp.workspace.builder import WorkspaceBuilder
from libtmux.server import Server

server = Server()
session = server.sessions.get(session_name="test", default=None)

if session:
    new_session = freeze(session)
    server.kill_session("test")
    builder = WorkspaceBuilder(session_config=new_session, server=server)
    builder.build()

error:

Traceback (most recent call last):
  File "/home/javier/dotfiles/bin/.bin/kitty-workspaces-d/test.py", line 12, in <module>
    builder.build()
    ~~~~~~~~~~~~~^^
  File "/home/javier/dotfiles/bin/.bin/kitty-workspaces-d/.venv/lib/python3.13/site-packages/tmuxp/workspace/builder.py", line 323, in build
    for pane, pane_config in self.iter_create_panes(window, window_config):
                             ~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/javier/dotfiles/bin/.bin/kitty-workspaces-d/.venv/lib/python3.13/site-packages/tmuxp/workspace/builder.py", line 552, in iter_create_panes
    enter = cmd.get("enter", enter)
            ^^^^^^^
AttributeError: 'str' object has no attribute 'get'

Reproduce the freeze-and-rebuild example, then inspect tmuxp/workspace/builder.py around iter_create_panes(), especially the cmd.get("enter", enter) call. Trace the frozen session data passed into WorkspaceBuilder and determine what input shape causes the AttributeError. Done means the reported example rebuilds the session without this exception, with coverage for the corrected behavior if the repository has a relevant test location.