Send decode error alert when EOED parsing fail

Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
diff --git a/library/ssl_tls13_server.c b/library/ssl_tls13_server.c
index 2e51572..65688cf 100644
--- a/library/ssl_tls13_server.c
+++ b/library/ssl_tls13_server.c
@@ -2910,7 +2910,12 @@
      * struct {} EndOfEarlyData;
      */
     ((void) ssl);
-    return buf == end ? 0 : MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE;
+    if (buf != end) {
+        MBEDTLS_SSL_PEND_FATAL_ALERT(MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR,
+                                     MBEDTLS_ERR_SSL_DECODE_ERROR);
+        return MBEDTLS_ERR_SSL_DECODE_ERROR;
+    }
+    return 0;
 }
 
 MBEDTLS_CHECK_RETURN_CRITICAL