Remove reactions when messages are removed, fixes #5164

packages/rocketchat-lib/server/models/Messages.coffee

@@ -244,6 +244,7 @@ RocketChat.models.Messages = new class extends RocketChat.models._Base
 				urls: []
 				mentions: []
 				attachments: []
+				reactions: []
 				editedAt: new Date()
 				editedBy:
 					_id: user._id

server/startup/migrations/v071.js

@@ -0,0 +1,9 @@
+RocketChat.Migrations.add({
+	version: 71,
+	up: function() {
+		//Removes the reactions on messages which are the system type "rm" ;)
+		RocketChat.models.Messages.find({ 't': 'rm', 'reactions': { $exists: true, $not: {$size: 0} } }, { t: 1 }).forEach(function(message) {
+			RocketChat.models.Messages.update({ _id: message._id }, { $set: { reactions: [] }});
+		});
+	}
+});