samples: net: http_server: Fix assertion on dynamic upload abort

The buffer pointer provided to the dynamic handler  should be verified
after checking the transaction status. In case upload was aborted and
underlying connection closed, the callback will get
HTTP_SERVER_DATA_ABORTED status w/o a pointer to any data.

Signed-off-by: Robert Lubos <[email protected]>

Author: rlubos

samples/net/sockets/http_server/src/main.c

@@ -76,14 +76,14 @@ static int echo_handler(struct http_client_ctx *client, enum http_data_status st
 	enum http_method method = client->method;
 	static size_t processed;
 
-	__ASSERT_NO_MSG(buffer != NULL);
-
 	if (status == HTTP_SERVER_DATA_ABORTED) {
 		LOG_DBG("Transaction aborted after %zd bytes.", processed);
 		processed = 0;
 		return 0;
 	}
 
+	__ASSERT_NO_MSG(buffer != NULL);
+
 	processed += len;
 
 	snprintf(print_str, sizeof(print_str), "%s received (%zd bytes)",