Mock responses when intentionally searching no indexes

Elasticsearch requests for a search with no matching indexes will
actually be rejected by shield with a 404, and we're doing such a search
automatically whenever we know there are no matching indexes that
contain data in the current time interval.

Instead of throwing a fatal error, we instead can handle this case
gracefully in the same way we do when there are no matching documents.

Fixes #5571

src/ui/public/courier/fetch/_call_client.js

@@ -93,7 +93,12 @@ define(function (require) {
           ignore_unavailable: true,
           preference: sessionId,
           body: body
-        }));
+        }))
+        .catch(function (err) {
+          return strategy.handleResponseError
+            ? strategy.handleResponseError(executable, err)
+            : Promise.reject(err);
+        });
       })
       .then(function (clientResp) {
         return strategy.getResponses(clientResp);

src/ui/public/courier/fetch/strategy/search.js

@@ -4,9 +4,32 @@ define(function (require) {
     var angular = require('angular');
     var toJson = require('ui/utils/aggressive_parse').toJson;
 
+    function emptyResponse() {
+      return { hits: { total: 0, hits: [] } };
+    };
+
     return {
       clientMethod: 'msearch',
 
+      /**
+       * Recover from a 404 when searching against no indexes
+       *
+       * If we get a 404 while intentionally searching for no indexes, we can
+       * simply mock an empty result since that is ultimately what kibana cares
+       * about.
+       *
+       * @param  {object} response - the client response from elasticsearch
+       * @return {Promise} - fulfilled by mock or rejected with original error
+       */
+      handleResponseError: function (requests, response) {
+        var is404 = _.get(response, 'status') === 404;
+        var isEmptyIndexList = _.get(response, 'body.error.index') === '[-*]';
+
+        return is404 && isEmptyIndexList
+          ? Promise.resolve({ responses: requests.map(emptyResponse) })
+          : Promise.reject(response);
+      },
+
       /**
        * Flatten a series of requests into as ES request body
        *