Better error handling.

Closes prose#113.

_includes/model.js

@@ -156,7 +156,7 @@ function loadSite(user, repo, branch, path, cb) {
 
     repo.getSha(branch, path, function(err, sha) {
       repo.getTree(sha, function(err, tree) {
-        if (err) cb("Not a valid Jekyll repository.");
+        if (err) return cb("Not found");
 
         var paths = _.compact(_.map(tree, function(file) {
           return file.type === "tree" ? (path ? path + "/" : "")+ file.path : null;

_includes/routers/application.js

@@ -48,6 +48,7 @@ routers.Application = Backbone.Router.extend({
   // #example-user/example-repo/gh-pages/path/to
   // #example-user/example-repo/gh-pages
   posts: function(url) {
+    if (url.split('/').length < 3) return app.instance.notify('error', 'Not Found');
     if (confirmExit()) {
       app.instance.posts.apply(this, this.extractURL(url));
     }

_includes/views/application.js

@@ -70,16 +70,16 @@ views.Application = Backbone.View.extend({
 
   posts: function (user, repo, branch, path) {
     loadSite(user, repo, branch, path, _.bind(function (err, data) {
-      if (err) return this.notify('error', 'Seems like the chosen repository is not a valid Jekyll site.');
+      if (err) return this.notify('error', 'The requested resource could not be found.');
       this.header.render();
       this.replaceMainView("posts", new views.Posts({ model: data, id: 'posts' }).render());
     }, this));
   },
 
   post: function (user, repo, branch, path, file, preview) {
     loadSite(user, repo, branch, path, _.bind(function (err, data) {
-      
-      if (err) return this.notify('error', 'Seems like the chosen repository is not a valid Jekyll site.');
+
+      if (err) return this.notify('error', 'The requested resource could not be found.');
       loadPost(user, repo, branch, path, file, _.bind(function (err, data) {
         data.preview = preview;
         this.header.render();