Fix Trace search time is null ,there is an error (#168)

* If Trace time is null ,there is an error

* add validation
diff --git a/src/routes/Trace/TraceSearch.js b/src/routes/Trace/TraceSearch.js
index 8e0cdaa..20e8c9a 100644
--- a/src/routes/Trace/TraceSearch.js
+++ b/src/routes/Trace/TraceSearch.js
@@ -210,7 +210,12 @@
     return (
       <Form onSubmit={this.handleSearch} layout="vertical">
         <FormItem label="Time Range">
-          {getFieldDecorator('range-time-picker')(
+          {getFieldDecorator('range-time-picker', {
+            rules: [{
+              required: true,
+              message: 'Please select the correct date',
+            }],
+          })(
             <RangePicker
               showTime
               disabledDate={current => current && current.valueOf() >= Date.now()}