Skip empty lines (#89)

src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/shared/ReadBuffer.kt

@@ -24,7 +24,7 @@ public class ReadBuffer {
             -1L -> return null
             0L -> {
                 buffer.skip(1)
-                ""
+                return null
             }
 
             else -> {

src/jvmTest/kotlin/shared/ReadBufferTest.kt

@@ -41,6 +41,13 @@ class ReadBufferTest {
         assertNull(readBuffer.readMessage())
     }
 
+    @Test
+    fun `skip empty line`() {
+        val readBuffer = ReadBuffer()
+        readBuffer.append("\n".toByteArray(StandardCharsets.UTF_8))
+        assertNull(readBuffer.readMessage())
+    }
+
     @Test
     fun `should be reusable after clearing`() {
         val readBuffer = ReadBuffer()