I got this bug from your mod :

[795295.573] [Gameplay] ERROR: UNIQUE constraint failed: Improvement_ValidFeatures.ImprovementType, Improvement_ValidFeatures.FeatureType
[795295.573] [Gameplay]: While executing - 'insert into Improvement_ValidFeatures('ImprovementType', 'FeatureType') values (?, ?);'
[795295.573] [Gameplay]: In XMLSerializer while inserting row into table insert into Improvement_ValidFeatures('ImprovementType', 'FeatureType') with values (IMPROVEMENT_LUMBER_MILL, FEATURE_JUNGLE, ).
[795295.573] [Gameplay]: In XMLSerializer while updating table Improvement_ValidFeatures from file NEWImprovements.xml.

It is due to a clash with an other mod, or from anything else ? What can I do ?