Add JsonObject field reading syntax sugar

formats/json/commonMain/src/kotlinx/serialization/json/JsonElement.kt

@@ -229,27 +229,51 @@ public class JsonArray(private val content: List<JsonElement>) : JsonElement(),
 public val JsonElement.jsonPrimitive: JsonPrimitive
     get() = this as? JsonPrimitive ?: error("JsonPrimitive")
 
+/**
+ * Returns content of the current element as JsonPrimitive or `null` if the current element is not a valid representation of JsonPrimitive
+ */
+public val JsonElement.jsonPrimitiveOrNull: JsonPrimitive?
+    get() = this as? JsonPrimitive
+
 /**
  * Convenience method to get current element as [JsonObject]
  * @throws IllegalArgumentException if current element is not a [JsonObject]
  */
 public val JsonElement.jsonObject: JsonObject
     get() = this as? JsonObject ?: error("JsonObject")
 
+/**
+ * Returns content of the current element as JsonObject or `null` if the current element is not a valid representation of JsonObject
+ */
+public val JsonElement.jsonObjectOrNull: JsonObject?
+    get() = this as? JsonObject
+
 /**
  * Convenience method to get current element as [JsonArray]
  * @throws IllegalArgumentException if current element is not a [JsonArray]
  */
 public val JsonElement.jsonArray: JsonArray
     get() = this as? JsonArray ?: error("JsonArray")
 
+/**
+ * Returns content of the current element as JsonArray or `null` if the current element is not a valid representation of JsonArray
+ */
+public val JsonElement.JsonArrayOrNull: JsonArray?
+    get() = this as? JsonArray
+
 /**
  * Convenience method to get current element as [JsonNull]
  * @throws IllegalArgumentException if current element is not a [JsonNull]
  */
 public val JsonElement.jsonNull: JsonNull
     get() = this as? JsonNull ?: error("JsonNull")
 
+/**
+ * Returns content of the current element as JsonNull or `null` if the current element is not a valid representation of JsonNull
+ */
+public val JsonElement.jsonNullOrNull: JsonNull?
+    get() = this as? JsonNull
+
 /**
  * Returns content of the current element as int
  * @throws NumberFormatException if current element is not a valid representation of number
@@ -347,3 +371,66 @@ internal fun unexpectedJson(key: String, expected: String): Nothing =
 
 // Use this function to avoid re-wrapping exception into NumberFormatException
 internal fun JsonPrimitive.parseLongImpl(): Long = StringJsonLexer(content).consumeNumericLiteralFully()
+
+/**
+ * Returns the JsonObject value associated with the given [key] in this [JsonObject],
+ * or null if the key is missing, the value is a string, or cannot be parsed as a JsonObject.
+ */
+public fun JsonObject.getJsonObjectOrNull(key: String): JsonObject? =
+    this[key]?.jsonObjectOrNull
+
+/**
+ * Returns the JsonArray value associated with the given [key] in this [JsonObject],
+ * or null if the key is missing, the value is a string, or cannot be parsed as a JsonArray.
+ */
+public fun JsonObject.getJsonArrayOrNull(key: String): JsonArray? =
+    this[key]?.JsonArrayOrNull
+
+/**
+ * Returns the JsonPrimitive value associated with the given [key] in this [JsonObject],
+ * or null if the key is missing, the value is a string, or cannot be parsed as a JsonPrimitive.
+ */
+public fun JsonObject.getJsonPrimitiveOrNull(key: String): JsonPrimitive? =
+    this[key]?.jsonPrimitiveOrNull
+
+/**
+ * Returns the int value associated with the given [key] in this [JsonObject],
+ * or null if the key is missing, the value is a string, or cannot be parsed as a int.
+ */
+public fun JsonObject.getIntOrNull(key: String): Int? =
+    this[key]?.jsonPrimitive?.takeIf { !it.isString }?.intOrNull
+
+/**
+ * Returns the long value associated with the given [key] in this [JsonObject],
+ * or null if the key is missing, the value is a string, or cannot be parsed as a long.
+ */
+public fun JsonObject.getLongOrNull(key: String): Long? =
+    this[key]?.jsonPrimitive?.takeIf { !it.isString }?.longOrNull
+
+/**
+ * Returns the boolean value associated with the given [key] in this [JsonObject],
+ * or null if the key is missing, the value is a string, or cannot be parsed as a boolean.
+ */
+public fun JsonObject.getBooleanOrNull(key: String): Boolean? =
+    this[key]?.jsonPrimitive?.takeIf { !it.isString }?.booleanOrNull
+
+/**
+ * Returns the double value associated with the given [key] in this [JsonObject],
+ * or null if the key is missing, the value is a string, or cannot be parsed as a double.
+ */
+public fun JsonObject.getDoubleOrNull(key: String): Double? =
+    this[key]?.jsonPrimitive?.takeIf { !it.isString }?.doubleOrNull
+
+/**
+ * Returns the float value associated with the given [key] in this [JsonObject],
+ * or null if the key is missing, the value is a string, or cannot be parsed as a float.
+ */
+public fun JsonObject.getFloatOrNull(key: String): Float? =
+    this[key]?.jsonPrimitive?.takeIf { !it.isString }?.floatOrNull
+
+/**
+ * Returns the string content associated with the given [key] in this [JsonObject],
+ * or null if the key is missing or the value is not a JSON string.
+ */
+public fun JsonObject.getStringOrNull(key: String): String? =
+    this[key]?.jsonPrimitive?.takeIf { it.isString }?.contentOrNull