Add docs about simple normalizer type verification

assets/scss/custom.scss

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 	--alert-best-practice-foreground-color: var(--ifm-color-success-contrast-foreground);
 	--alert-best-practice-border-color: #a3148c;
+
+	--alert-added-version-background-color: #ff7400;
+	--alert-added-version-foreground-color: #190700;
+	--alert-added-version-border-color: #ff4d00;
 }
 
 /* For readability concerns, you should choose a lighter palette in dark mode. */
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 	--alert-best-practice-foreground-color: var(--ifm-color-success-contrast-foreground);
 	--alert-best-practice-border-color: #e617c3;
+
+	--alert-added-version-background-color: #ff7400;
+	--alert-added-version-foreground-color: #190700;
+	--alert-added-version-border-color: #ff4d00;
 }
 
 [data-theme='dark'],

blog/2025-07-03-simple-normalizer-verifier.mdx

@@ -0,0 +1,9 @@
+---
+title: "Simple Normalizer: JSON Types Verifier"
+authors: [jannik]
+tags: [simple-normalizer]
+---
+
+[Simple Normalizer now verifies][1] that all of your simple object normalizers are returning the correct types.
+
+[1]: /docs/php/symfony/simple-normalizer/#returning-invalid-values

docs/php/symfony/simple-normalizer/index.mdx

@@ -1,4 +1,5 @@
 import {LinkList} from "../../../../src/components/Link/LinkList";
+import {AddedBadge} from "../../../../src/components/AddedBadge";
 
 # Simple Normalizer
 
@@ -155,3 +156,35 @@ public function normalize (object $value, array $context, SimpleNormalizer $norm
 	// ...
 }
 ```
+
+
+## Returning Invalid Values
+
+<AddedBadge package="21torr/simple-normalizer" version="1.4.0" />
+
+All values in the generated JSON must be of valid JSON types, that includes: scalars, arrays and empty objects.
+
+:::info
+Empty objects are allowed, as JSON encoding an empty array[^1] will always encode to `[]`, but `json_encode(new stdClass()) === "{}"`.
+:::
+
+However, due to performance reasons, the normalizer does not check for valid values. If you return an invalid value, it will be silently ignored (and in the end passed to `json_encode()`):
+
+```php
+class MyNormalizer implements SimpleObjectNormalizerInterface
+{
+	public function normalize (object $value, array $context, SimpleNormalizer $normalizer) : mixed
+	{
+		assert($value instanceof MyObject);
+
+		// this will be silently ignored
+		return new SomeObject();
+	}
+}
+```
+
+This is never intended behavior and is now validated. This check is only enabled in `debug` mode, so you can still use the normalizer in production without performance overhead.
+
+
+
+[^1]: PHP doesn't distinguish between empty arrays and empty objects, so `json_encode` can only encode to one of them. You can configure it with the constant `JSON_FORCE_OBJECT`, but that is a global setting, and most of the time you want to have different behavior in the same normalization process.

package.json

@@ -11,10 +11,11 @@
 		"write-translations": "docusaurus write-translations"
 	},
 	"dependencies": {
-		"@docusaurus/core": "^3.8.0",
-		"@docusaurus/faster": "^3.8.0",
-		"@docusaurus/preset-classic": "^3.8.0",
-		"@docusaurus/theme-classic": "^3.8.0",
+		"@docusaurus/core": "^3.8.1",
+		"@docusaurus/faster": "^3.8.1",
+		"@docusaurus/preset-classic": "^3.8.1",
+		"@docusaurus/theme-classic": "^3.8.1",
+		"@iconify/react": "^6.0.0",
 		"@mdx-js/react": "^3.1.0",
 		"clsx": "^2.1.1",
 		"prism-react-renderer": "^2.4.1",
@@ -23,8 +24,8 @@
 		"react-dom": "^19.1.0"
 	},
 	"devDependencies": {
-		"@docusaurus/module-type-aliases": "3.8.0",
-		"@docusaurus/types": "^3.8.0",
+		"@docusaurus/module-type-aliases": "3.8.1",
+		"@docusaurus/types": "^3.8.1",
 		"@tsconfig/docusaurus": "^2.0.3",
 		"@types/node": "^22.15.29",
 		"@types/react": "^19.1.6",