It's all explained here at the forum, at the sticky posts!
One just needs to read before one writes...
And again, explaining it the 1034234233. time:
Error lines starting with /ESOUI/ are base game lua code, no addon.
As the base game code always may trigger addon code too you might see a lot of such error messages where it tells you something like a "callback object" or "event" did something and then addon code errored in the end at the top of the "what was called in which order" stack.
Best to narrow this down is:
1. Find out what triggers the error and when it does, e.g. opening the map or zoning to a new zone, or is it always directly after a reloadUI was done etc.
2. Write down which other addons you are currently using. You can use an addon like "Addon Selector" to save the current active addons and libraries as a pack/profile so you can load them again later on.
Disable all other addons except the one that is shown: HarvestMap, and then try if the error still happens.
If it still happens: Tell the HarvestMap dev at the addon comments, not here at the forums please.
Search for the addon via the addon search, find the version you are currently using and post at these comments.
If the error with HarvestMap alone will not occur: The error is not on HarvestMap but some other addons. Find out which of your other addons, in combination with HarvestMap, might cause this. If the addon erroring is about maps I'd start to enable other addons related to maps first to see if they, together with HarvestMap, are a problem.
About MiniMap by fyrakin: Update to the new version by Masteroshi please, as the other original one is old and broken!