Do not fail if npm-shrinwrap.json does not exit

Gruntfile.js

@@ -106,13 +106,20 @@ module.exports = function (grunt) {
     grunt.log.writeln('');
   }
 
-  var duplicatedModules = lockedDependencies.checkDuplicatedDependencies(require('./npm-shrinkwrap.json'), LOCKED_MODULES_TO_VALIDATE);
-  if (duplicatedModules.length > 0) {
-    grunt.log.fail('############### /!\\ CAUTION /!\\ #################');
-    grunt.log.fail('Duplicated dependencies found in npm-shrinkwrap.json file.');
-    grunt.log.fail(JSON.stringify(duplicatedModules, null, 4));
-    grunt.log.fail('#################################################');
-    process.exit(1);
+  var duplicatedModules;
+
+  try {
+    duplicatedModules = lockedDependencies.checkDuplicatedDependencies(require('./npm-shrinkwrap.json'), LOCKED_MODULES_TO_VALIDATE);
+  } catch (e) {
+    grunt.log.fail('Lock file "npm-shrinkwrap.json" does not exist. Skiping duplicated modules check.');
+  } finally {
+    if (duplicatedModules.length > 0) {
+      grunt.log.fail('############### /!\\ CAUTION /!\\ #################');
+      grunt.log.fail('Duplicated dependencies found in npm-shrinkwrap.json file.');
+      grunt.log.fail(JSON.stringify(duplicatedModules, null, 4));
+      grunt.log.fail('#################################################');
+      process.exit(1);
+    }
   }
 
   duplicatedModules = lockedDependencies.checkDuplicatedDependencies(require('./package-lock.json'), LOCKED_MODULES_TO_VALIDATE);