Freeze in item::deserialize (during submap::load)

[Aivean]

Describe the bug

When loading submap game freezes.

From the brief debugging I think it tries to deserialize invalid item json, fails, and then probably fails to advance parsing cursor, infinitely retrying to deserialize the invalid item.

Steps To Reproduce

1. Load the savefile from this issue Game freeze when telling NPC to construct woodchip floor in basecamp  #41220
2. Walk diagonally in the NE direction (see gif)
3. Observe freeze

Expected behavior

If that is indeed caused by invalid item, the item should be skipped and error displayed, no freeze should happen.

Screenshots

Profiling:

Versions and configuration

• OS: MacOs
  • OS Version: Name: Mac OS X; Version: 10.14; Build: 18A391;
• Game Version: 0.E-8298-g838ce8c564 [64-bit]
• Graphics Version: Tiles
• Game Language: English [en]
• Mods loaded: [
  Dark Days Ahead [dda],
  No Rail Stations [No_Rail_Stations],
  Graphical Overmap [Graphical_Overmap]
  ]

Additional context

I'm not 100% sure, but that might be a regression from #45617 or #45635.

[Aivean]

@anothersimulacrum , if you have a chance, please take a look.

[anothersimulacrum]

So far, I think I need to go through and note down/fix all the places this is failing to visit members. Past that, we'll see what's up.