sending images through messages works

backend/models/Message.js

@@ -25,7 +25,7 @@ const Message = sequelize.define('Message', {
   },
   content: {
     type: DataTypes.TEXT,
-    allowNull: false
+    allowNull: true
   },
   isRead: {
     type: DataTypes.BOOLEAN,
@@ -36,7 +36,15 @@ const Message = sequelize.define('Message', {
     allowNull: true
   }
 }, {
-  timestamps: true
+  timestamps: true,
+  validate: {
+    contentOrImage() {
+      const hasContent = this.content && this.content.trim().length > 0;
+      if (!hasContent && !this.imageFilename) {
+        throw new Error('Message must have content or an image');
+      }
+    }
+  }
 });
 
 module.exports = Message;