php - vue.js2.0下出现warn错误

出现这个问题，请问如何解决，求解

代码如下：

varapp=newVue({

el:'#app',data:{steps:[{name:'HelloVue!',completed:false},{name:'HelloWorld!',completed:false}],newStep:''},mounted:function(){this.fetchSteps();},methods:{fetchSteps:function(){this.$http.get('/tasks/2/steps').then((response)=>{//successVue.set(this,'steps',response.body);},(response)=>{//errorresponse.status;});},addStep:function(){this.steps.push({name:this.newStep,completed:false});this.newStep='';},complete:function(step){step.completed=true;},removeStep:function(step){varindex=this.steps.indexOf(step);this.steps.splice(index,1);},editStep:function(step){this.removeStep(step);this.newStep=step.name;this.$refs.newStep.focus();},toggleComplete:function(step){step.completed=false;},completeAll:function(){this.steps.forEach(function(step){step.completed=true;});},clearComplete:function(){//this.steps=[];kthis.steps=this.steps.filter(function(step){return!step.completed;});}},computed:{inProcess:function(){returnthis.steps.filter(function(step){if(step.completed==false)returnstep;})},processed:function(){returnthis.steps.filter(function(step){if(step.completed==true)returnstep;})},completions:function(){returnthis.steps.filter(function(step){returnstep.completed;});},remaings:function(){returnthis.steps.filter(function(step){return!step.completed;});}}

})