fixed phpstan found errors

Author: jkuchar

composer.json

@@ -6,11 +6,23 @@
             "email": "[email protected]"
         }
     ],
+    "scripts": {
+        "verify": [
+            "@test",
+            "@phpstan"
+        ],
+        "test": "vendor/bin/tester examples/",
+        "phpstan": "vendor/bin/phpstan analyze -l 7 --configuration phpstan.neon --error-format compact src"
+    },
     "require": {
         "ramsey/uuid": "^3.8.0"
     },
     "require-dev": {
-        "nette/tester": "^2.1.0"
+        "nette/tester": "^2.1.0",
+        "phpstan/phpstan": "^0.11.2",
+        "grifart/phpstan-oneline": "^0.2.1",
+        "phpstan/phpstan-strict-rules": "^0.11",
+        "rector/rector": "^0.4.1"
     },
     "autoload": {
         "psr-4": {