test: fix flow errors (#383)

Author: 38elements

src/wrappers/wrapper.js

@@ -452,18 +452,21 @@ export default class Wrapper implements BaseWrapper {
     if (!this.isVueComponent || !this.vm) {
       throwError('wrapper.setProps() can only be called on a Vue instance')
     }
-    if (!this.vm.$options.propsData) {
+    if (this.vm && this.vm.$options && !this.vm.$options.propsData) {
       this.vm.$options.propsData = {}
     }
     Object.keys(data).forEach((key) => {
       // $FlowIgnore : Problem with possibly null this.vm
       if (this.vm._props) {
         this.vm._props[key] = data[key]
+        // $FlowIgnore : Problem with possibly null this.vm.$props
         this.vm.$props[key] = data[key]
+        // $FlowIgnore : Problem with possibly null this.vm.$options
         this.vm.$options.propsData[key] = data[key]
       } else {
         // $FlowIgnore : Problem with possibly null this.vm
         this.vm[key] = data[key]
+        // $FlowIgnore : Problem with possibly null this.vm.$options
         this.vm.$options.propsData[key] = data[key]
       }
     })