guests can no longer attempt to join a group, #2588

public/src/client/groups/details.js

@@ -58,7 +58,7 @@ define('forum/groups/details', ['iconSelect', 'vendor/colorpicker/colorpicker',
 						if (!err) {
 							ajaxify.refresh();
 						} else {
-							app.alertError(err);
+							app.alertError(err.message);
 						}
 					});
 					break;

src/groups.js

@@ -599,11 +599,15 @@ var async = require('async'),
 	};
 
 	Groups.requestMembership = function(groupName, uid, callback) {
-		db.setAdd('group:' + groupName + ':pending', uid, callback);
-		plugins.fireHook('action:groups.requestMembership', {
-			groupName: groupName,
-			uid: uid
-		});
+		if (parseInt(uid, 10) > 0) {
+			db.setAdd('group:' + groupName + ':pending', uid, callback);
+			plugins.fireHook('action:groups.requestMembership', {
+				groupName: groupName,
+				uid: uid
+			});
+		} else {
+			callback(new Error('[[error:not-logged-in]]'));
+		}
 	};
 
 	Groups.acceptMembership = function(groupName, uid, callback) {