Mod doesn't check if "parts" field is already added.

[rheirman]

Apparently the mod doesn't check properly whether other mods already add the "parts" field when you're adding in statparts, resulting in errors like:

XML RimWorld.StatDef defines the same field twice: parts.
I suggest fixing this by adding in some extra checks in your xpaths. What I generally do is this:

<Operation Class="PatchOperationSequence">
	<success>Always</success>
	<operations>
		<li Class = "PatchOperationAdd">
			<xpath>Defs/StatDef[defName="[defName here]"]/parts</xpath>
			<value>
				<li Class="[class here]"/>
			</value>
		</li>
	</operations>
</Operation>
<Operation Class="PatchOperationSequence">
	<success>Always</success>
	<operations>
		<li Class = "PatchOperationAdd">
			<xpath>Defs/StatDef[defName="[defName here]" and not (parts)]</xpath>
			<value>
				<parts>
					<li Class="[class here]"/>
				</parts>
			</value>
		</li>
	</operations>
</Operation>

It's not very elegant, since you need two patches now, but it does prevent errors when other mods also add in parts.