fixed issues with Moodle 3.11 compatibility

amd/src/modedit-modal.js

@@ -12,6 +12,21 @@ import {replaceNodeContents} from 'core/templates';
 //import {markFormSubmitted} from 'core_form/changechecker'; // Moodle 4.00+ only
 //import {notifyFormSubmittedByJavascript} from 'core_form/events'; // Moodle 4.00+ only
 
+/* Moodle 3.11 safe import for when needed
+let markFormSubmitted = () => {};
+let notifyFormSubmittedByJavascript = () => {};
+
+import('core_form/changechecker').then((ns) => {
+    debug.info(ns);
+    if(ns.markFormSubmitted) {
+        markFormSubmitted = ns.markFormSubmitted;
+    }
+    if(ns.notifyFormSubmittedByJavascript) {
+        notifyFormSubmittedByJavascript = ns.notifyFormSubmittedByJavascript;
+    }
+}).catch(()=>{});
+*/
+
 export default {
     install(Vue/*,options*/){
 

amd/src/page-edit-plan.js

@@ -9,7 +9,8 @@
 import {get_string,get_strings} from 'core/str';
 import {call} from 'core/ajax';
 import notification from 'core/notification';
-import {resetAllFormDirtyStates} from 'core_form/changechecker';
+
+//import {resetAllFormDirtyStates} from 'core_form/changechecker';  // Moodle 4.00+ only
 
 import Vue from './vue/vue';
 
@@ -36,6 +37,16 @@ Vue.use(BootstrapVue);
 
 const debug = new Debugger("treestudyplan");
 
+let resetAllFormDirtyStates = () => {};
+import('core_form/changechecker').then((ns) => {
+    debug.info(ns);
+    if(ns.resetAllFormDirtyStates) {
+        resetAllFormDirtyStates = ns.resetAllFormDirtyStates;
+    }
+}).catch(()=>{});
+
+
+
 let strings = load_strings({
     studyplan: {
         studyplan_select_placeholder: 'studyplan_select_placeholder',

amd/src/util/mform-helper.js

@@ -14,6 +14,21 @@ import Debugger from './debugger';
 //import {markFormSubmitted} from 'core_form/changechecker'; // Moodle 4.00+ only
 //import {notifyFormSubmittedByJavascript} from 'core_form/events'; // Moodle 4.00+ only
 
+/* Moodle 3.11 safe import for when needed
+let markFormSubmitted = () => {};
+let notifyFormSubmittedByJavascript = () => {};
+
+import('core_form/changechecker').then((ns) => {
+    debug.info(ns);
+    if(ns.markFormSubmitted) {
+        markFormSubmitted = ns.markFormSubmitted;
+    }
+    if(ns.notifyFormSubmittedByJavascript) {
+        notifyFormSubmittedByJavascript = ns.notifyFormSubmittedByJavascript;
+    }
+}).catch(()=>{});
+*/
+
 /**
  * Create a random UUID in both secure and insecure contexts
  * @returns UUID