What I was doing: I tried to convert my save into the map editor before it came up with this error before it loaded.

The mod Solar Calculator (0.5.32) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event solar-calc::on_configuration_changed
LuaGuiElement API call when LuaGuiElement was invalid.
stack traceback:
[C]: in function 'index'
__solar-calc/scripts/views/surface-menu-view.lua:276: in function 'r_event_handler'
solar-calc/scripts/kgui/reactive/reactive-base.lua:62: in function 'notify_gui'
solar-calc/scripts/kgui/reactive/reactive-base.lua:89: in function 'notify_subscribers'
solar-calc/scripts/kgui/reactive/rproperty.lua:47: in function 'set'
solar-calc/scripts/kgui/reactive/rproperty.lua:34: in function 'update'
solar-calc/scripts/kgui/reactive/reactive-base.lua:84: in function 'notify_subscribers'
solar-calc/scripts/kgui/reactive/rproperty.lua:47: in function 'set'
solar-calc/scripts/init.lua:71: in function 'reinit_planets'
solar-calc/scripts/migrations/migrations.lua:81: in function <solar-calc/scripts/migrations/migrations.lua:54>

End of my log file:

====================================================================================================
Leaving event script for on_configuration_changed
Event data: mod_changes = {Fill4Me = {new_version = "0.12.0", old_version = "0.11.2"}, PlutoniumEnergy = {new_version = "1.7.3", old_version = "1.7.2"}, Robot256Lib = {new_version = "2.0.4", old_version = "2.0.3"}, Waterfill_v17 = {new_version = "2.0.3", old_version = "2.0.2"}, ["aai-loaders"] = {new_version = "0.2.4", old_version = "0.2.3"}, ["bigger-artillery"] = {new_version = "0.7.2", old_version = "0.7.1"}, ["factorissimo-2-notnotmelon"] = {new_version = "3.5.8", old_version = "3.5.5"}, holographic_signs = {new_version = "2.0.5", old_version = "2.0.4"}, ["mining-patch-planner"] = {new_version = "1.6.20", old_version = "1.6.18"}}, mod_startup_settings_changed = true, migration_applied = true, tick = 1252675
(@CharacterModHelper/control.lua: 607)
====================================================================================================

107.747 Script @Milestones/scripts/presets_loader.lua:145: Reloading presets
107.748 Script @Milestones/scripts/presets_loader.lua:158: New presets found: {}
107.749 Script @Milestones/scripts/presets_loader.lua:159: New list of valid presets: {"Empty", "Vanilla", "Space Age"}
108.248 Error ParallelScenarioConverter.cpp:59: The mod Solar Calculator (0.5.32) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event solar-calc::on_configuration_changed
LuaGuiElement API call when LuaGuiElement was invalid.
stack traceback:
[C]: in function 'index'
__solar-calc/scripts/views/surface-menu-view.lua:276: in function 'r_event_handler'
solar-calc/scripts/kgui/reactive/reactive-base.lua:62: in function 'notify_gui'
solar-calc/scripts/kgui/reactive/reactive-base.lua:89: in function 'notify_subscribers'
solar-calc/scripts/kgui/reactive/rproperty.lua:47: in function 'set'
solar-calc/scripts/kgui/reactive/rproperty.lua:34: in function 'update'
solar-calc/scripts/kgui/reactive/reactive-base.lua:84: in function 'notify_subscribers'
solar-calc/scripts/kgui/reactive/rproperty.lua:47: in function 'set'
solar-calc/scripts/init.lua:71: in function 'reinit_planets'
solar-calc/scripts/migrations/migrations.lua:81: in function <solar-calc/scripts/migrations/migrations.lua:54>
108.489 Error AppManagerStates.cpp:2187: The mod Solar Calculator (0.5.32) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event solar-calc::on_configuration_changed
LuaGuiElement API call when LuaGuiElement was invalid.
stack traceback:
[C]: in function 'index'
__solar-calc/scripts/views/surface-menu-view.lua:276: in function 'r_event_handler'
solar-calc/scripts/kgui/reactive/reactive-base.lua:62: in function 'notify_gui'
solar-calc/scripts/kgui/reactive/reactive-base.lua:89: in function 'notify_subscribers'
solar-calc/scripts/kgui/reactive/rproperty.lua:47: in function 'set'
solar-calc/scripts/kgui/reactive/rproperty.lua:34: in function 'update'
solar-calc/scripts/kgui/reactive/reactive-base.lua:84: in function 'notify_subscribers'
solar-calc/scripts/kgui/reactive/rproperty.lua:47: in function 'set'
solar-calc/scripts/init.lua:71: in function 'reinit_planets'
solar-calc/scripts/migrations/migrations.lua:81: in function <solar-calc/scripts/migrations/migrations.lua:54>

The way you got this error is very unusual, I never used the map editor myself.
But the bug was caused by another reason, which could also happen even in normal saves.
Should be fixed now. Big thanks for the report, I was starting to think I made a bugless software, haha!

The mod Solar Calculator (0.5.42) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event solar-calc::on_gui_checked_state_changed (ID 3)
solar-calc/scripts/views/block-cell-view.lua:171: Assert failed!
stack traceback:
[C]: in function 'error'
solar-calc/scripts/views/block-cell-view.lua:171: in function 'gui_event_handler'
solar-calc/scripts/kgui/kgui.lua:203: in function 'handle_event'
solar-calc/scripts/main.lua:47: in function <solar-calc/scripts/main.lua:43>

https://i.imgur.com/E65Udg7.png

I don't remember what I clicked in the UI,

This is weird. When you click an already checked radio button, it creates an event as if it becomes unchecked, behaves like a checkbox. But that's only in code, visually it stays checked... This wasn't the behavior in Factorio 1.1. Seems to be a 2.0 bug.
I'll probably have to create a workaround and write a bug report for the devs...