I got the following red errors on startup. It looks like the XML it's complaining about is in this mod's patches for Rim-Effect Core, which I'm not subscribed to. If Windows' timestamps are to be trusted, it looks like this file may have been updated today.

Could not find type named MaterialPatchingUtility.PatchOperationBalanceMaterial from node <li Class="MaterialPatchingUtility.PatchOperationBalanceMaterial"><xpath>Defs/ThingDef[@ParentName = "BaseHumanMakeableGun" and label[contains(text(), "alliance")]]/costList/Plasteel</xpath><percentage>30</percentage><material>VMEu_CarbonFiber</material></li>

XML error: <xpath>Defs/ThingDef[@ParentName = "BaseHumanMakeableGun" and label[contains(text(), "alliance")]]/costList/Plasteel</xpath> doesn't correspond to any field in type PatchOperation. Context: <li Class="MaterialPatchingUtility.PatchOperationBalanceMaterial"><xpath>Defs/ThingDef[@ParentName = "BaseHumanMakeableGun" and label[contains(text(), "alliance")]]/costList/Plasteel</xpath><percentage>30</percentage><material>VMEu_CarbonFiber</material></li>

XML error: <percentage>30</percentage> doesn't correspond to any field in type PatchOperation. Context: <li Class="MaterialPatchingUtility.PatchOperationBalanceMaterial"><xpath>Defs/ThingDef[@ParentName = "BaseHumanMakeableGun" and label[contains(text(), "alliance")]]/costList/Plasteel</xpath><percentage>30</percentage><material>VMEu_CarbonFiber</material></li>

XML error: <material>VMEu_CarbonFiber</material> doesn't correspond to any field in type PatchOperation. Context: <li Class="MaterialPatchingUtility.PatchOperationBalanceMaterial"><xpath>Defs/ThingDef[@ParentName = "BaseHumanMakeableGun" and label[contains(text(), "alliance")]]/costList/Plasteel</xpath><percentage>30</percentage><material>VMEu_CarbonFiber</material></li>

Could not find type named MaterialPatchingUtility.PatchOperationBalanceMaterial from node <li Class="MaterialPatchingUtility.PatchOperationBalanceMaterial"><xpath>Defs/ThingDef[@ParentName = "BaseHumanMakeableGun" and label[contains(text(), "alliance")]]/costList/Plasteel</xpath><percentage>40</percentage><material>VMEu_CarbonFiber</material></li>

XML error: <xpath>Defs/ThingDef[@ParentName = "BaseHumanMakeableGun" and label[contains(text(), "alliance")]]/costList/Plasteel</xpath> doesn't correspond to any field in type PatchOperation. Context: <li Class="MaterialPatchingUtility.PatchOperationBalanceMaterial"><xpath>Defs/ThingDef[@ParentName = "BaseHumanMakeableGun" and label[contains(text(), "alliance")]]/costList/Plasteel</xpath><percentage>40</percentage><material>VMEu_CarbonFiber</material></li>

XML error: <percentage>40</percentage> doesn't correspond to any field in type PatchOperation. Context: <li Class="MaterialPatchingUtility.PatchOperationBalanceMaterial"><xpath>Defs/ThingDef[@ParentName = "BaseHumanMakeableGun" and label[contains(text(), "alliance")]]/costList/Plasteel</xpath><percentage>40</percentage><material>VMEu_CarbonFiber</material></li>

XML error: <material>VMEu_CarbonFiber</material> doesn't correspond to any field in type PatchOperation. Context: <li Class="MaterialPatchingUtility.PatchOperationBalanceMaterial"><xpath>Defs/ThingDef[@ParentName = "BaseHumanMakeableGun" and label[contains(text(), "alliance")]]/costList/Plasteel</xpath><percentage>40</percentage><material>VMEu_CarbonFiber</material></li>