Gracefully handle empty keymaps and menus

Closes atom/settings-view#310

spec/fixtures/packages/package-with-empty-keymap/package.json

@@ -0,0 +1,4 @@
+{
+  "name": "package-with-empty-keymap",
+  "version": "1.0.0"
+}

spec/fixtures/packages/package-with-empty-menu/package.json

@@ -0,0 +1,4 @@
+{
+  "name": "package-with-empty-menu",
+  "version": "1.0.0"
+}

spec/package-manager-spec.coffee

@@ -273,6 +273,14 @@ describe "PackageManager", ->
               expect(atom.keymaps.findKeyBindings(keystrokes:'ctrl-n', target:element1[0])[0].command).toBe 'keymap-2'
               expect(atom.keymaps.findKeyBindings(keystrokes:'ctrl-y', target:element3[0])).toHaveLength 0
 
+        describe "when the keymap file is empty", ->
+          it "does not throw an error on activation", ->
+            waitsForPromise ->
+              atom.packages.activatePackage("package-with-empty-keymap")
+
+            runs ->
+              expect(atom.packages.isPackageActive("package-with-empty-keymap")).toBe true
+
       describe "menu loading", ->
         beforeEach ->
           atom.contextMenu.definitions = []
@@ -311,6 +319,14 @@ describe "PackageManager", ->
               expect(atom.contextMenu.templateForElement(element)[1].label).toBe "Menu item 1"
               expect(atom.contextMenu.templateForElement(element)[2]).toBeUndefined()
 
+        describe "when the menu file is empty", ->
+          it "does not throw an error on activation", ->
+            waitsForPromise ->
+              atom.packages.activatePackage("package-with-empty-menu")
+
+            runs ->
+              expect(atom.packages.isPackageActive("package-with-empty-menu")).toBe true
+
       describe "stylesheet loading", ->
         describe "when the metadata contains a 'stylesheets' manifest", ->
           it "loads stylesheets from the stylesheets directory as specified by the manifest", ->

src/package.coffee

@@ -206,13 +206,13 @@ class Package
     if @bundledPackage and packagesCache[@name]?
       @keymaps = (["#{atom.packages.resourcePath}#{path.sep}#{keymapPath}", keymapObject] for keymapPath, keymapObject of packagesCache[@name].keymaps)
     else
-      @keymaps = @getKeymapPaths().map (keymapPath) -> [keymapPath, CSON.readFileSync(keymapPath)]
+      @keymaps = @getKeymapPaths().map (keymapPath) -> [keymapPath, CSON.readFileSync(keymapPath) ? {}]
 
   loadMenus: ->
     if @bundledPackage and packagesCache[@name]?
       @menus = (["#{atom.packages.resourcePath}#{path.sep}#{menuPath}", menuObject] for menuPath, menuObject of packagesCache[@name].menus)
     else
-      @menus = @getMenuPaths().map (menuPath) -> [menuPath, CSON.readFileSync(menuPath)]
+      @menus = @getMenuPaths().map (menuPath) -> [menuPath, CSON.readFileSync(menuPath) ? {}]
 
   getKeymapPaths: ->
     keymapsDirPath = path.join(@path, 'keymaps')