fix: improve typing using phpstan and fix some errors identified by phpstan

Author: SamMousa

.github/workflows/main.yml

@@ -26,6 +26,8 @@ jobs:
 
     - name: Install dependencies
       run: composer install --prefer-dist --no-progress --no-interaction --no-suggest
+    - name: Run PHPStan
+      run: php vendor/bin/phpstan
 
     - name: Run test suite
       run: |

composer.json

@@ -27,8 +27,9 @@
         "yiisoft/yii2-app-advanced": "dev-master",
         "codeception/verify": "^3.0",
         "codemix/yii2-localeurls": "^1.7",
-        "codeception/module-asserts": "^3.0",
-        "codeception/module-filesystem": "^3.0"
+        "codeception/module-asserts": ">= 3.0",
+        "codeception/module-filesystem": "> 3.0",
+        "phpstan/phpstan": "^1.10"
     },
     "autoload":{
         "classmap": ["src/"]

phpstan.neon

@@ -0,0 +1,20 @@
+#includes:
+#    - phpstan-baseline.neon
+parameters:
+    reportUnmatchedIgnoredErrors: true
+    dynamicConstantNames:
+      - CONSOLE
+      - YII_DEBUG
+    level: 5
+    paths:
+      - src
+    checkMaybeUndefinedVariables: true
+    checkGenericClassInNonGenericObjectType: false
+    ignoreErrors:
+        # All Yii setters accept `null` but their phpdoc is incorrect.
+        - message: '~^Parameter #1 \$value of method yii\\web\\Request::set(.*)\(\) expects (.*), null given.$~'
+          path: 'src/'
+        - message: '~^Variable \$_COOKIE in isset\(\) always exists and is not nullable.$~'
+          path: 'src/'
+    stubFiles:
+        - tests/Yii.stub