diff --git a/.gitattributes b/.gitattributes
new file mode 100644
index 0000000..4126d6c
--- /dev/null
+++ b/.gitattributes
@@ -0,0 +1,14 @@
+/tests export-ignore
+/vendor export-ignore
+
+/README.md export-ignore
+/LICENSE export-ignore
+/Makefile export-ignore
+/phpmd.xml export-ignore
+/phpunit.xml export-ignore
+/phpstan.neon.dist export-ignore
+/infection.json.dist export-ignore
+
+/.github export-ignore
+/.gitignore export-ignore
+/.gitattributes export-ignore
diff --git a/composer.json b/composer.json
index 9258894..64e9596 100644
--- a/composer.json
+++ b/composer.json
@@ -10,8 +10,6 @@
         "psr",
         "json",
         "array",
-        "psr-4",
-        "psr-12",
         "serializer",
         "tiny-blocks"
     ],
@@ -21,6 +19,10 @@
             "homepage": "https://github.com/gustavofreze"
         }
     ],
+    "support": {
+        "issues": "https://github.com/tiny-blocks/serializer/issues",
+        "source": "https://github.com/tiny-blocks/serializer"
+    },
     "config": {
         "sort-packages": true,
         "allow-plugins": {
@@ -41,14 +43,16 @@
         "php": "^8.2"
     },
     "require-dev": {
-        "infection/infection": "^0.29",
         "phpmd/phpmd": "^2.15",
+        "phpstan/phpstan": "^1",
         "phpunit/phpunit": "^11",
+        "infection/infection": "^0.29",
         "squizlabs/php_codesniffer": "^3.10"
     },
     "scripts": {
         "phpcs": "phpcs --standard=PSR12 --extensions=php ./src",
         "phpmd": "phpmd ./src text phpmd.xml --suffixes php --ignore-violations-on-exit",
+        "phpstan": "phpstan analyse -c phpstan.neon.dist --quiet --no-progress",
         "test": "phpunit --log-junit=report/coverage/junit.xml --coverage-xml=report/coverage/coverage-xml --coverage-html=report/coverage/coverage-html tests",
         "fix-style": "phpcbf ./src --extensions=php",
         "test-mutation": "infection --only-covered --logger-html=report/coverage/mutation-report.html --coverage=report/coverage --min-msi=100 --min-covered-msi=100 --threads=4",
@@ -56,7 +60,8 @@
         "test-mutation-no-coverage": "infection --only-covered --min-msi=100 --threads=4",
         "review": [
             "@phpcs",
-            "@phpmd"
+            "@phpmd",
+            "@phpstan"
         ],
         "tests": [
             "@test",
diff --git a/infection.json.dist b/infection.json.dist
index e9bacf3..01fde44 100644
--- a/infection.json.dist
+++ b/infection.json.dist
@@ -1,15 +1,15 @@
 {
     "timeout": 10,
     "testFramework": "phpunit",
-    "tmpDir": "report/",
+    "tmpDir": "report/infection/",
     "source": {
         "directories": [
             "src"
         ]
     },
     "logs": {
-        "text": "report/logs/infection-text.log",
-        "summary": "report/logs/infection-summary.log"
+        "text": "report/infection/logs/infection-text.log",
+        "summary": "report/infection/logs/infection-summary.log"
     },
     "mutators": {
         "@default": true,
diff --git a/phpstan.neon.dist b/phpstan.neon.dist
new file mode 100644
index 0000000..ceb7a86
--- /dev/null
+++ b/phpstan.neon.dist
@@ -0,0 +1,11 @@
+parameters:
+  paths:
+    - src
+  level: 9
+  tmpDir: report/phpstan
+  ignoreErrors:
+    - '#method toArray#'
+    - '#object_or_class#'
+    - '#with no value type specified in#'
+    - '#return type has no value type specified#'
+  reportUnmatchedIgnoredErrors: false
diff --git a/src/Internal/ArraySerializer.php b/src/Internal/ArraySerializer.php
index 8d1d4c6..03861ac 100644
--- a/src/Internal/ArraySerializer.php
+++ b/src/Internal/ArraySerializer.php
@@ -16,7 +16,7 @@ public function __construct(private iterable $iterable)
     public function toArray(SerializeKeys $serializeKeys = SerializeKeys::PRESERVE): array
     {
         $mapper = new Mapper(serializeKeys: $serializeKeys);
-        $shouldPreserveKeys = $serializeKeys && $serializeKeys->shouldPreserveKeys();
+        $shouldPreserveKeys = $serializeKeys->shouldPreserveKeys();
 
         $elements = is_array($this->iterable)
             ? $this->iterable
diff --git a/src/Internal/JsonSerializer.php b/src/Internal/JsonSerializer.php
index d86ab4b..3c674b3 100644
--- a/src/Internal/JsonSerializer.php
+++ b/src/Internal/JsonSerializer.php
@@ -9,8 +9,14 @@
     public function serialize(array $data): string
     {
         $isSingleItem = count($data) === 1;
-        $dataToSerialize = $isSingleItem ? $data[0] : $data;
+        $dataToSerialize = $isSingleItem ? ($data[0] ?? null) : $data;
 
-        return json_encode($dataToSerialize, JSON_PRESERVE_ZERO_FRACTION);
+        $json = json_encode($dataToSerialize, JSON_PRESERVE_ZERO_FRACTION);
+
+        if (!is_string($json) || $json === 'null') {
+            return $isSingleItem ? '{}' : '[]';
+        }
+
+        return $json;
     }
 }
diff --git a/src/Internal/Mappers/Mapper.php b/src/Internal/Mappers/Mapper.php
index 2ac83b6..31b50ce 100644
--- a/src/Internal/Mappers/Mapper.php
+++ b/src/Internal/Mappers/Mapper.php
@@ -10,7 +10,7 @@ final class Mapper
 {
     private ValueMapper $valueMapper;
 
-    public function __construct(?SerializeKeys $serializeKeys)
+    public function __construct(SerializeKeys $serializeKeys)
     {
         $this->valueMapper = new ValueMapper(serializeKeys: $serializeKeys);
     }
diff --git a/src/Serializer.php b/src/Serializer.php
index c3759e4..fc8d636 100644
--- a/src/Serializer.php
+++ b/src/Serializer.php
@@ -15,8 +15,14 @@ interface Serializer
     /**
      * Serializes the object to a JSON string.
      *
-     * @param SerializeKeys $serializeKeys Optional parameter to define how keys
-     *                                     should be serialized (default: PRESERVE).
+     * The key serialization behavior can be customized using the `SerializeKeys` enum:
+     *  - `SerializeKeys::DISCARD`: Discards the array keys.
+     *  - `SerializeKeys::PRESERVE`: Preserves the array keys.
+     *
+     * By default, `SerializeKeys::PRESERVE` is used.
+     *
+     * @param SerializeKeys $serializeKeys Optional parameter to define whether array keys
+     *                                     should be preserved or discarded.
      * @return string The JSON string representing the object.
      */
     public function toJson(SerializeKeys $serializeKeys = SerializeKeys::PRESERVE): string;
@@ -24,8 +30,14 @@ public function toJson(SerializeKeys $serializeKeys = SerializeKeys::PRESERVE):
     /**
      * Converts the object to an array.
      *
-     * @param SerializeKeys $serializeKeys Optional parameter to define how keys
-     *                                     should be serialized (default: PRESERVE).
+     * The key serialization behavior can be customized using the `SerializeKeys` enum:
+     *  - `SerializeKeys::DISCARD`: Discards the array keys.
+     *  - `SerializeKeys::PRESERVE`: Preserves the array keys.
+     *
+     * By default, `SerializeKeys::PRESERVE` is used.
+     *
+     * @param SerializeKeys $serializeKeys Optional parameter to define whether array keys
+     *                                     should be preserved or discarded.
      * @return array<Key, Value> The array representation of the object.
      */
     public function toArray(SerializeKeys $serializeKeys = SerializeKeys::PRESERVE): array;
diff --git a/tests/IterableSerializerTest.php b/tests/IterableSerializerTest.php
index 100fcd5..903f80d 100644
--- a/tests/IterableSerializerTest.php
+++ b/tests/IterableSerializerTest.php
@@ -73,6 +73,18 @@ public function testSerializeToArray(iterable $iterable, array $expected): void
         self::assertSame($expected, $actual);
     }
 
+    public function testSerializeMultipleInvalidItemsReturnsEmptyJsonArray(): void
+    {
+        /** @Given multiple invalid items (e.g., functions that cannot be serialized) */
+        $serializer = new IterableSerializer(iterable: [fn(): null => null, fn(): null => null]);
+
+        /** @When attempting to serialize the invalid items */
+        $actual = $serializer->toJson();
+
+        /** @Then the output should be an empty JSON array */
+        self::assertSame('[[],[]]', $actual);
+    }
+
     public static function toJsonDataProvider(): array
     {
         $spTimeZone = new DateTimeZone('America/Sao_Paulo');
diff --git a/tests/Models/Serializable/Service.php b/tests/Models/Serializable/Service.php
new file mode 100644
index 0000000..b874915
--- /dev/null
+++ b/tests/Models/Serializable/Service.php
@@ -0,0 +1,18 @@
+<?php
+
+declare(strict_types=1);
+
+namespace TinyBlocks\Serializer\Models\Serializable;
+
+use Closure;
+use TinyBlocks\Serializer\Serializer;
+use TinyBlocks\Serializer\SerializerAdapter;
+
+final class Service implements Serializer
+{
+    use SerializerAdapter;
+
+    public function __construct(public Closure $action)
+    {
+    }
+}
diff --git a/tests/SerializerAdapterTest.php b/tests/SerializerAdapterTest.php
index 92f056a..a5bd253 100644
--- a/tests/SerializerAdapterTest.php
+++ b/tests/SerializerAdapterTest.php
@@ -9,6 +9,7 @@
 use TinyBlocks\Serializer\Models\Serializable\Address;
 use TinyBlocks\Serializer\Models\Serializable\Addresses;
 use TinyBlocks\Serializer\Models\Serializable\Country;
+use TinyBlocks\Serializer\Models\Serializable\Service;
 use TinyBlocks\Serializer\Models\Serializable\Shipping;
 use TinyBlocks\Serializer\Models\Serializable\State;
 
@@ -34,6 +35,18 @@ public function testSerializeToJson(Shipping $shipping, string $expected): void
         self::assertJsonStringEqualsJsonString($expected, $actual);
     }
 
+    public function testSerializeSingleInvalidItemReturnsEmptyJsonObject(): void
+    {
+        /** @Given a single invalid item (e.g., a function that cannot be serialized) */
+        $service = new Service(action: fn(): int => 0);
+
+        /** @When attempting to serialize the invalid item */
+        $actual = $service->toJson();
+
+        /** @Then the output should be an empty JSON object */
+        self::assertSame('{}', $actual);
+    }
+
     public static function shippingDataProviderForArray(): array
     {
         $shippingWithNoAddresses = new Shipping(id: 1, addresses: new Addresses());