Issues with history view functions

[ashwch]

I've been trying to use the history views in a SPA, and I've come across the following issues:

• Refresh fails if DebugToolbar._store is still being updated in parallel as dict can't be mutated while iteration is happening on it.
• Switch functionality doesn't work on rows loaded after refresh due to missing signature.
• Old expired rows remain in FE and result in 500 error(history_sidebar) as the store_id is not present in DebugToolbar anymore

Please let me know if any of this is an intended behaviour.