getting a red log warning while having this mod in the modlist together with vanilla furniture expanded security ( https://psteamcommunity.yuanyoumao.com/workshop/filedetails/?id=1845154007 ) so more of an incompatibility than a bug:
XML RimWorld.StatDef defines the same field twice: parts.

Field contents: .

Whole XML:

<StatDef><defName>RangedWeapon_Cooldown</defName><label>ranged cooldown</label><description>How long it takes to recover after firing this weapon.</description><category>Weapon_Ranged</category><defaultBaseValue>1</defaultBaseValue><minValue>0.01</minValue><toStringStyle>FloatTwo</toStringStyle><formatString>{0} s</formatString><showIfUndefined>false</showIfUndefined><displayPriorityInCategory>5106</displayPriorityInCategory><scenarioRandomizable>true</scenarioRandomizable><parts><li Class="VFECore.Misc.StatPart_Ammo" /><li Class="VFESecurity.StatPart_AmmoCrate"><valueFactor>0.8</valueFactor></li></parts><parts><li Class="ModularWeapons.StatPart_MWCooldown" /></parts></StatDef>
UnityEngine.StackTraceUtility:ExtractStackTrace ()
Verse.Log:Error (string)
Verse.DirectXmlToObject:ObjectFromXml<RimWorld.StatDef> (System.Xml.XmlNode,bool)
Verse.DirectXmlToObject:ObjectFromXmlReflection<RimWorld.StatDef> (System.Xml.XmlNode,bool)
Verse.DirectXmlLoader:DefFromNode (System.Xml.XmlNode,Verse.LoadableXmlAsset)
Verse.LoadedModManager:ParseAndProcessXML (System.Xml.XmlDocument,System.Collections.Generic.Dictionary`2<System.Xml.XmlNode, Verse.LoadableXmlAsset>)
Verse.LoadedModManager:LoadAllActiveMods ()
Verse.PlayDataLoader:DoPlayLoad ()
Verse.PlayDataLoader:LoadAllPlayData (bool)
Verse.Root/<>c:<Start>b__6_1 ()
Verse.LongEventHandler:RunEventFromAnotherThread (System.Action)
Verse.LongEventHandler/<>c:<UpdateCurrentAsynchronousEvent>b__27_0 ()
System.Threading.ThreadHelper:ThreadStart_Context (object)
System.Threading.ExecutionContext:RunInternal (System.Threading.ExecutionContext,System.Threading.ContextCallback,object,bool)
System.Threading.ExecutionContext:Run (System.Threading.ExecutionContext,System.Threading.ContextCallback,object,bool)
System.Threading.ExecutionContext:Run (System.Threading.ExecutionContext,System.Threading.ContextCallback,object)
System.Threading.ThreadHelper:ThreadStart ()

Just a general error: when adding or removing parts, some of the positive/negative color coding is backwards. A ranged cooldown decreasing is shown as red, when it's actually a benefit. Similarly, lower mass should be green, not red.

Example: standard bolt-action rifle. Adding a bipod shows accuracy boosts as green (correct), but also a +0.3s increase in cooldown and a +0.3kg increase in mass as green (incorrect).

These bugs fixed;
・field conflicts on XML
・incorrect collor on stats change

Thank you!

I add modular weapon using scenario editor and when generating map there's an error that says "RimWorld by Ludeon Studios - Unity 2019.4.30f1_e8c891080a1f" then the game closed. It works just fine when i remove modular weapon from the scenario

@Emay - I would imagine that's because when you add it via scenario editor, you don't get a chance to customize it, and a dev-spawned modular weapon probably isn't the same as a modular weapon that happens to have a default configuration

@Postal - It did work just fine for the first time I added it. I can select which part to choose at the start of the game. But, the next time I create new game it got error like what i said

Originally posted by Emay:

I add modular weapon using scenario editor and when generating map there's an error that says "RimWorld by Ludeon Studios - Unity 2019.4.30f1_e8c891080a1f" then the game closed. It works just fine when i remove modular weapon from the scenario

This happens when I use "Start near".
You can avoid this by using "Start with".

anyway, I'll try to solve this.

I'm not sure if it's a bug from another mod causing this, but when I created a modular LMG, it fired incendiary launcher projectiles, not bullets. and it didn't even leave fire behind; I'll try to make another and see if it replicates.

I think it's possible that the mod causes the pawn to use a projectile from the previously equipped weapon, because i had a pawn pick up a modular charge rifle after using molotovs, and they continued throwing molotovs with the charge rifle equipped

>>projectile from the previously equipped weapon

Not confirmed in my environment.
It may be caused by other mods.

Not sure if it's a bug or one of the many mods I have installed breaking this, but the modular SMG is not working. The pawn using said SMG just stands around when drafted and will not shoot, even when manually assigned a target.

>>SMG not working
not confirmed, too.

If you want me to fix your bugs, PLEASE report mods you using with! NOT "not sure" !
I don't matter how long it is, that's why I made this thread!

I'll take a look, sorry for the lack of additional info. it's not happening with any other weapons as far as I can tell, though.

I have, in the way of extra equipment mods...
-vanilla armory expanded (grenades, laser, quickdraw)
-vanilla weapons expanded
-proper shotguns
-simple sidearms

thinking about it, it might be the sidearm mod bugging out as well

I changed the mod order around and it works now. Putting this mod higher up fixed the issue. Also, mod list will take a while to make. The mods that could possibly interfere would be "Run and Gun", "Use Your Gun!", and possibly "Where is my weapon?" Most of my other mods do not change gun mechanics, and these were all ahead of this mod on the mod list.