create app dir if not exists

package-lock.json

@@ -34,6 +34,15 @@
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             "dev": true
         },
+        "@types/mkdirp": {
+            "version": "0.5.2",
+            "resolved": "https://registry.npmjs.org/@types/mkdirp/-/mkdirp-0.5.2.tgz",
+            "integrity": "sha512-U5icWpv7YnZYGsN4/cmh3WD2onMY0aJIiTE6+51TwJCttdHvtCYmkBNOobHlXwrJRL0nkH9jH4kD+1FAdMN4Tg==",
+            "dev": true,
+            "requires": {
+                "@types/node": "10.0.8"
+            }
+        },
         "@types/node": {
             "version": "10.0.8",
             "resolved": "https://registry.npmjs.org/@types/node/-/node-10.0.8.tgz",
@@ -3102,7 +3111,6 @@
             "version": "0.5.1",
             "resolved": "https://registry.npmjs.org/mkdirp/-/mkdirp-0.5.1.tgz",
             "integrity": "sha1-MAV0OOrGz3+MR2fzhkjWaX11yQM=",
-            "dev": true,
             "requires": {
                 "minimist": "0.0.8"
             },
@@ -3110,8 +3118,7 @@
                 "minimist": {
                     "version": "0.0.8",
                     "resolved": "https://registry.npmjs.org/minimist/-/minimist-0.0.8.tgz",
-                    "integrity": "sha1-hX/Kv8M5fSYluCKCYuhqp6ARsF0=",
-                    "dev": true
+                    "integrity": "sha1-hX/Kv8M5fSYluCKCYuhqp6ARsF0="
                 }
             }
         },