The mod The Blueprint Designer Lab (1.0.3) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event BlueprintLab_design::on_gui_click (ID 1)
LuaEntity API call when LuaEntity was invalid.
stack traceback:
[C]: in function 'index'
__BlueprintLab_design/scripts/logic.lua:88: in function 'ToTheWorld'
BlueprintLab_design/scripts/logic.lua:9: in function 'OnLabButton'
BlueprintLab_design/scripts/gui.lua:46: in function <BlueprintLab_design/scripts/gui.lua:44>

I can reload game, still in lab just cant leave without it crashing. when i reload tho it seems like the game thinks im not in the lab...

I also just received an error when attempting to exit the lab.
I had just created a Blueprint and while still in hand, I attempted to exit.
I reloaded my save and was able to exit if I did not have the blueprint in hand.

The mod The Blueprint Designer Lab (1.0.3) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event BlueprintLab_design::on_gui_click (ID 1)
LuaPlayer doesn't contain key clean_cursor.
stack traceback:
[C]: in function 'index'
__BlueprintLab_design/scripts/logic.lua:130: in function 'ReturnBlueprintImport'
BlueprintLab_design/scripts/logic.lua:93: in function 'ToTheWorld'
BlueprintLab_design/scripts/logic.lua:9: in function 'OnLabButton'
BlueprintLab_design/scripts/gui.lua:46: in function <BlueprintLab_design/scripts/gui.lua:44>

I have the exact same error:

The mod The Blueprint Designer Lab (1.0.3) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event BlueprintLab_design::on_gui_click (ID 1)
LuaPlayer doesn't contain key clean_cursor.