Avoid exposing raw response to exception message

Author: kpavlov

kotlin-sdk-core/src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/types/serializers.kt

@@ -44,7 +44,7 @@ private fun JsonElement.getType(): String = requireNotNull(getTypeOrNull()) { "M
 @Throws(SerializationException::class)
 private fun JsonElement.asJsonObject(): JsonObject {
     if (this !is JsonObject) {
-        throw SerializationException("Invalid response. JsonObject expected, got: $this")
+        throw SerializationException("Invalid response. JsonObject expected, got: ${this::class.simpleName}")
     }
     val jsonObject = this.jsonObject
     return jsonObject

kotlin-sdk-core/src/commonTest/kotlin/io/modelcontextprotocol/kotlin/sdk/types/JsonRpcTest.kt

@@ -417,7 +417,7 @@ class JsonRpcTest {
             McpJson.decodeFromString<JSONRPCMessage>("[\"just a string\"]")
         }
 
-        exception.message shouldBe "Invalid response. JsonObject expected, got: [\"just a string\"]"
+        exception.message shouldBe "Invalid response. JsonObject expected, got: JsonArray"
     }
 
     @Test

kotlin-sdk-core/src/commonTest/kotlin/io/modelcontextprotocol/kotlin/sdk/types/ResourcesTest.kt

@@ -259,7 +259,7 @@ class ResourcesTest {
             McpJson.decodeFromString<ResourceContents>("\"just a string\"")
         }
 
-        exception.message shouldBe "Invalid response. JsonObject expected, got: \"just a string\""
+        exception.message shouldBe "Invalid response. JsonObject expected, got: JsonLiteral"
     }
 
     @Test