Guard against calling wikipedia service with empty query

modules/services/wikipedia.js

@@ -6,6 +6,11 @@ var wikipedia = {},
 
 export function init() {
     wikipedia.search = function(lang, query, callback) {
+        if (!query) {
+            callback([]);
+            return;
+        }
+
         lang = lang || 'en';
         jsonpRequest(endpoint.replace('en', lang) +
             qsString({
@@ -17,14 +22,23 @@ export function init() {
                 callback: '{callback}',
                 srsearch: query
             }), function(data) {
-                if (!data.query) return;
+                if (!data || !data.query || !data.query.search) {
+                    callback([]);
+                    return;
+                }
                 callback(query, data.query.search.map(function(d) {
                     return d.title;
                 }));
-            });
+            }
+        );
     };
 
     wikipedia.suggestions = function(lang, query, callback) {
+        if (!query) {
+            callback('', []);
+            return;
+        }
+
         lang = lang || 'en';
         jsonpRequest(endpoint.replace('en', lang) +
             qsString({
@@ -35,11 +49,21 @@ export function init() {
                 callback: '{callback}',
                 search: query
             }), function(d) {
+                if (!d || d.error) {
+                    callback('', []);
+                    return;
+                }
                 callback(d[0], d[1]);
-            });
+            }
+        );
     };
 
     wikipedia.translations = function(lang, title, callback) {
+        if (!title) {
+            callback({});
+            return;
+        }
+
         jsonpRequest(endpoint.replace('en', lang) +
             qsString({
                 action: 'query',
@@ -49,6 +73,11 @@ export function init() {
                 lllimit: 500,
                 titles: title
             }), function(d) {
+                if (!d || d.error) {
+                    callback({});
+                    return;
+                }
+
                 var list = d.query.pages[Object.keys(d.query.pages)[0]],
                     translations = {};
                 if (list && list.langlinks) {
@@ -57,7 +86,8 @@ export function init() {
                     });
                     callback(translations);
                 }
-            });
+            }
+        );
     };
 
     return wikipedia;