diff --git a/src/Utils.js b/src/Utils.js
index 03e841a3..a80f3808 100644
--- a/src/Utils.js
+++ b/src/Utils.js
@@ -67,7 +67,11 @@ export default function Utils (Y) {
       this._eventListener[name] = listener.filter(e => e !== f)
     }
     emit (name, value) {
-      (this._eventListener[name] || []).forEach(l => l(value))
+      let listener = this._eventListener[name] || []
+      if (name === 'error' && listener.length === 0) {
+        console.error(value)
+      }
+      listener.forEach(l => l(value))
     }
     destroy () {
       this._eventListener = null
diff --git a/src/y-memory.js b/src/y-memory.js
index 67a593f2..7744814d 100644
--- a/src/y-memory.js
+++ b/src/y-memory.js
@@ -1,4 +1,3 @@
-
 import extendRBTree from './RedBlackTree'
 
 export default function extend (Y) {
@@ -48,9 +47,13 @@ export default function extend (Y) {
     }
     transact (makeGen) {
       const t = new Transaction(this)
-      while (makeGen != null) {
-        makeGen.call(t)
-        makeGen = this.getNextRequest()
+      try {
+        while (makeGen != null) {
+          makeGen.call(t)
+          makeGen = this.getNextRequest()
+        }
+      } catch (e) {
+        this.y.emit('error', e)
       }
     }
     destroy () {