replace mergeObject with foundry.utils.mergeObject

module/actor/actor-sheet.js

@@ -14,7 +14,7 @@ import {
 export default class DeltaGreenActorSheet extends ActorSheet {
   /** @override */
   static get defaultOptions() {
-    return mergeObject(super.defaultOptions, {
+    return foundry.utils.mergeObject(super.defaultOptions, {
       classes: ["deltagreen", "sheet", "actor"],
       template: "systems/deltagreen/templates/actor/actor-sheet.html",
       width: 700,

module/actor/actor.js

@@ -74,15 +74,13 @@ export default class DeltaGreenActor extends Actor {
 
     system.wp.max = system.statistics.pow.value;
 
-    try{
+    try {
       system.health.max = Math.ceil(
         (system.statistics.con.value + system.statistics.str.value) / 2,
       );
-    }
-    catch(ex){
+    } catch (ex) {
       system.health.max = 10;
     }
-    
 
     system.skills.ritual = {
       label: "Ritual",
@@ -229,10 +227,9 @@ export default class DeltaGreenActor extends Actor {
       system.sanity.adaptations.helplessness.isAdapted = false;
     }
 
-    if(system.sanity.value <= system.sanity.currentBreakingPoint){
+    if (system.sanity.value <= system.sanity.currentBreakingPoint) {
       system.sanity.breakingPointHit = true;
-    }
-    else{
+    } else {
       system.sanity.breakingPointHit = false;
     }
 
@@ -277,7 +274,7 @@ export default class DeltaGreenActor extends Actor {
   static async create(data, options = {}) {
     data.prototypeToken = data.prototypeToken || {};
     if (data.type === "agent") {
-      mergeObject(
+      foundry.utils.mergeObject(
         data.prototypeToken,
         {
           actorLink: true, // this will make the 'Link Actor Data' option for a token is checked by default. So changes to the token sheet will reflect to the actor sheet.

module/item/item-sheet.js

@@ -7,7 +7,7 @@
 export default class DeltaGreenItemSheet extends ItemSheet {
   /** @override */
   static get defaultOptions() {
-    return mergeObject(super.defaultOptions, {
+    return foundry.utils.mergeObject(super.defaultOptions, {
       classes: ["deltagreen", "sheet", "item"],
       width: 520,
       height: 600,