I started New game with TradeRoute 0.0.1 updated it to TradeRoute 0.0.4 version.

And when the new version tryed create a new city i got this

The mod TradeRouteOverhaul (0.0.4) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event TradeRouteOverhaul::on_chunk_generated (ID 12)
TradeRouteOverhaul/control.lua:763: attempt to index field 'bad_trade_map' (a nil value)
stack traceback:
TradeRouteOverhaul/control.lua:763: in function 'spawn_city'
TradeRouteOverhaul/control.lua:101: in function <TradeRouteOverhaul/control.lua:98>

There were also a lot of migrated/removed mall-2-?-?-?-?-? and mall-4-?-?-?-?-? content.

This has been tested when only TradeRouteOverhaul mod was present.

i havent even tried migration support yet. moving a few malls around resulted in hundreds of icons and a few thousand recipes wanting legacy support.
instead the previous versions of the mod are available to continue playing saves in their version.