#576 warn errors in watcher getters

Author: yyx990803

src/watcher.js

@@ -72,7 +72,9 @@ p.get = function () {
   var value
   try {
     value = this.getter.call(vm, vm)
-  } catch (e) {}
+  } catch (e) {
+    _.warn(e)
+  }
   // use JSON.stringify to "touch" every property
   // so they are all tracked as dependencies for
   // deep watching

test/unit/specs/watcher_spec.js

@@ -374,4 +374,9 @@ describe('Watcher', function () {
     expect(watcher.cbs.length).toBe(2)
   })
 
+  it('warn getter errors', function () {
+    var watcher = new Watcher(vm, 'd.e + c', spy)
+    expect(_.warn).toHaveBeenCalled()
+  })
+
 })