[IMP] mail: completely clean records after deletion

This will reduce memory leaks.

Side-effect of this PR:

Accessing a field after the record is deleting is no longer supported. It was
never meant to be, but some async code relied on this behavior to check the
(non-)existence of relation fields, with an implicit check on the current record
existence.

-> After this PR, the existence check of current record needs to be explicit,
before accessing any field.

Part of task-2850875

Part-of: odoo/odoo#90934

addons/mail/static/src/model/model_manager.js

@@ -138,8 +138,7 @@ export class ModelManager {
         /**
          * Create the messaging singleton record.
          */
-        const messaging = this.models['Messaging'].insert(values);
-        Object.assign(odoo.__DEBUG__, { messaging });
+        this.models['Messaging'].insert(values);
         this.messagingCreatedPromise.resolve();
         await this.messaging.start();
         this.messagingInitializedPromise.resolve();
@@ -204,8 +203,7 @@ export class ModelManager {
      * @returns {boolean}
      */
     exists(model, record) {
-        const existingRecord = model.__records[record.localId];
-        return Boolean(existingRecord && existingRecord === record);
+        return Boolean(record.localId);
     }
 
     /**
@@ -655,7 +653,7 @@ export class ModelManager {
             get: function getFromProxy(record, prop) {
                 if (
                     !model.__fieldMap[prop] &&
-                    !['_super', 'then'].includes(prop) &&
+                    !['_super', 'then', 'localId'].includes(prop) &&
                     typeof prop !== 'symbol' &&
                     !(prop in record)
                 ) {
@@ -736,6 +734,9 @@ export class ModelManager {
             if (field.fieldType === 'relation') {
                 // ensure inverses are properly unlinked
                 field.parseAndExecuteCommands(record, unlinkAll(), { allowWriteReadonly: true });
+                if (!record.exists()) {
+                    return; // current record might have been deleted from causality
+                }
             }
         }
         this._createdRecordsComputes.delete(record);
@@ -756,7 +757,10 @@ export class ModelManager {
                 infoList,
             });
         }
+        delete record.__values;
+        delete record.__listeners;
         delete model.__records[record.localId];
+        delete record.localId;
     }
 
     /**
@@ -1215,6 +1219,10 @@ export class ModelManager {
             for (const field of model.__fieldList) {
                 Object.defineProperty(model.prototype, field.fieldName, {
                     get: function getFieldValue() { // this is bound to record
+                        if (!this.exists()) {
+                            // Deprecated, allows reading fields on deleted records. Use exists() instead.
+                            return undefined;
+                        }
                         if (this.modelManager._listeners.size) {
                             if (!this.modelManager._listenersObservingLocalId.has(this.localId)) {
                                 this.modelManager._listenersObservingLocalId.set(this.localId, new Map());

addons/mail/static/src/models/drop_zone_view.js

@@ -65,9 +65,11 @@ registerModel({
             if (this._isDragSourceExternalFile(ev.dataTransfer)) {
                 if (this.chatterOwner) {
                     await this.chatterOwner.fileUploader.uploadFiles(ev.dataTransfer.files);
+                    return;
                 }
                 if (this.composerViewOwner) {
                     await this.composerViewOwner.fileUploader.uploadFiles(ev.dataTransfer.files);
+                    return;
                 }
             }
         },

addons/mail/static/src/models/messaging.js

@@ -14,10 +14,14 @@ registerModel({
     name: 'Messaging',
     identifyingFields: [],
     lifecycleHooks: {
+        _created() {
+            odoo.__DEBUG__.messaging = this;
+        },
         _willDelete() {
             if (this.env.services['legacy_bus_service']) {
                 this.env.services['legacy_bus_service'].off('window_focus', null, this._handleGlobalWindowFocus);
             }
+            delete odoo.__DEBUG__.messaging;
         },
     },
     recordMethods: {

addons/mail/static/src/models/thread_cache.js

@@ -292,6 +292,9 @@ registerModel({
                 return;
             }
             const fetchedMessages = await this._loadMessages();
+            if (!this.exists()) {
+                return;
+            }
             for (const threadView of this.threadViews) {
                 threadView.addComponentHint('messages-loaded', { fetchedMessages });
             }