Correctly pass tap errors into the ErrorBanner component (#1443)

We have a new format for displaying errors in ErrorBanner. 
When a websocket error occurred, we'd pass in text where ErrorBanner 
expects and object. This PR puts the websocket errors in an object

Also clean up the display of the error by removing redundant text.

web/app/js/components/ErrorBanner.jsx

@@ -47,9 +47,9 @@ class ErrorMessage extends React.Component {
       <Row gutter={0}>
         <div className="error-message-container">
           <Col span={20}>
-            <div><b>Error:</b> {status} {statusText}</div>
-            { !error ? null : <div><b>Message:</b> {error}</div> }
-            <div><b>URL:</b> {url}</div>
+            { !status && !statusText ? null : <div>{status} {statusText}</div> }
+            { !error ? null : <div>{error}</div> }
+            { !url ? null : <div>{url}</div> }
           </Col>
           <Col span={4}>
             <div className="dismiss" onClick={this.hideMessage} role="presentation">Dismiss X</div>

web/app/js/components/ErrorModal.jsx

@@ -4,7 +4,7 @@ import PropTypes from 'prop-types';
 import React from 'react';
 import { Button, Icon, Modal, Switch } from 'antd';
 
-// max characters we displaly for error messages before truncating them
+// max characters we display for error messages before truncating them
 const maxErrorLength = 500;
 
 export default class ErrorModal extends React.Component {

web/app/js/components/Namespace.jsx

@@ -53,7 +53,7 @@ class Namespaces extends React.Component {
       metrics: {},
       pendingRequests: false,
       loaded: false,
-      error: ''
+      error: null
     };
   }
 

web/app/js/components/Tap.jsx

@@ -91,7 +91,7 @@ class Tap extends React.Component {
     }));
     this.setState({
       awaitingWebSocketConnection: false,
-      error: ""
+      error: null
     });
   }
 
@@ -104,14 +104,16 @@ class Tap extends React.Component {
 
     if (!e.wasClean) {
       this.setState({
-        error: `Websocket [${e.code}] ${e.reason}`
+        error: {
+          error: `Websocket [${e.code}] ${e.reason}`
+        }
       });
     }
   }
 
   onWebsocketError = e => {
     this.setState({
-      error: e.message
+      error: { error: e.message }
     });
 
     this.stopTapStreaming();
@@ -588,7 +590,7 @@ class Tap extends React.Component {
     return (
       <div>
         {!this.state.error ? null :
-        <ErrorBanner message={this.state.error} onHideMessage={() => this.setState({ error: "" })} />}
+        <ErrorBanner message={this.state.error} onHideMessage={() => this.setState({ error: null })} />}
 
         <PageHeader header="Tap" />
         {this.renderTapForm()}