added isBeingDeleted to be able to recognize that note is being deleted while still leaving it accessible

src/becca/entities/attribute.js

@@ -113,7 +113,13 @@ class Attribute extends AbstractEntity {
      * @returns {Note|null}
      */
     getNote() {
-        return this.becca.getNote(this.noteId);
+        const note = this.becca.getNote(this.noteId);
+
+        if (!note) {
+            throw new Error(`Note '${this.noteId}' of attribute '${this.attributeId}', type '${this.type}', name '${this.name}' does not exist.`);
+        }
+
+        return note;
     }
 
     /**

src/becca/entities/branch.js

@@ -187,9 +187,7 @@ class Branch extends AbstractEntity {
 
             log.info("Deleting note " + note.noteId);
 
-            // marking note as deleted as a signal to event handlers that the note is being deleted
-            // (isDeleted is being checked against becca)
-            delete this.becca.notes[note.noteId];
+            this.becca.notes[note.noteId].isBeingDeleted = true;
 
             for (const attribute of note.getOwnedAttributes()) {
                 attribute.markAsDeleted(deleteId);

src/becca/entities/note.js

@@ -72,6 +72,8 @@ class Note extends AbstractEntity {
         this.utcDateCreated = utcDateCreated || dateUtils.utcNowDateTime();
         /** @type {string} */
         this.utcDateModified = utcDateModified;
+        /** @type {boolean} - set during the deletion operation, before it is completed (removed from becca completely) */
+        this.isBeingDeleted = false;
 
         // ------ Derived attributes ------
 
@@ -1327,7 +1329,7 @@ class Note extends AbstractEntity {
     }
 
     get isDeleted() {
-        return !(this.noteId in this.becca.notes);
+        return !(this.noteId in this.becca.notes) || this.isBeingDeleted;
     }
 
     /**