handel null and undefined

ms.js

@@ -26,6 +26,9 @@ var y = d * 365.25;
 
 module.exports = function (val, options) {
   options = options || {};
+
+  if (val == null || val == undefined) return undefined;
+
   var type = typeof val;
   if (type === 'string' && val.length > 0) {
     return parse(val);

package-lock.json

 {
   "name": "nexpietime",
-  "version": "1.0.0",
+  "version": "1.0.2",
   "lockfileVersion": 2,
   "requires": true,
   "packages": {
     "": {
-      "version": "1.0.0",
+      "version": "1.0.2",
       "license": "ISC",
-      "dependencies": {
-        "ms": "^2.1.3"
-      },
       "devDependencies": {
         "chai": "^4.2.0",
         "chai-each": "0.0.1",
@@ -169,11 +166,6 @@
       "integrity": "sha512-gKO5uExCXvSm6zbF562EvM+rd1kQDnB9AZBbiQVzf1ZmdDpxUSvpnAaVOP83N/31mRK8Ml8/VE8DMvsAZQ+7wg==",
       "dev": true
     },
-    "node_modules/ms": {
-      "version": "2.1.3",
-      "resolved": "https://registry.npmjs.org/ms/-/ms-2.1.3.tgz",
-      "integrity": "sha512-6FlzubTLZG3J2a/NVCAleEhjzq5oxgHyaCU9yYXvcLsvoVaHJq/s5xXI6/XXP6tz7R9xAOtHnSO/tXtF3WRTlA=="
-    },
     "node_modules/nise": {
       "version": "1.5.3",
       "resolved": "https://registry.npmjs.org/nise/-/nise-1.5.3.tgz",
@@ -383,11 +375,6 @@
       "integrity": "sha512-gKO5uExCXvSm6zbF562EvM+rd1kQDnB9AZBbiQVzf1ZmdDpxUSvpnAaVOP83N/31mRK8Ml8/VE8DMvsAZQ+7wg==",
       "dev": true
     },
-    "ms": {
-      "version": "2.1.3",
-      "resolved": "https://registry.npmjs.org/ms/-/ms-2.1.3.tgz",
-      "integrity": "sha512-6FlzubTLZG3J2a/NVCAleEhjzq5oxgHyaCU9yYXvcLsvoVaHJq/s5xXI6/XXP6tz7R9xAOtHnSO/tXtF3WRTlA=="
-    },
     "nise": {
       "version": "1.5.3",
       "resolved": "https://registry.npmjs.org/nise/-/nise-1.5.3.tgz",

package.json

 {
   "name": "nexpietime",
-  "version": "1.0.1",
+  "version": "1.0.2",
   "description": "",
   "main": "index.js",
   "scripts": {