MINOR: h3: report error on HEADERS/DATA parsing

Inspect return code of HEADERS/DATA parsing functions and use a BUG_ON
to signal an error. The stream should be closed to handle the error
in a more clean fashion.
diff --git a/src/h3.c b/src/h3.c
index b9e4d5e..7cecb5d 100644
--- a/src/h3.c
+++ b/src/h3.c
@@ -231,6 +231,7 @@
 static int h3_decode_qcs(struct qcs *qcs, int fin, void *ctx)
 {
 	struct buffer *rxbuf = &qcs->rx.buf;
+	int ret;
 
 	h3_debug_printf(stderr, "%s: STREAM ID: %llu\n", __func__, qcs->by_id.key);
 	if (!b_data(rxbuf))
@@ -261,10 +262,14 @@
 
 		switch (ftype) {
 		case H3_FT_DATA:
-			h3_data_to_htx(qcs, rxbuf, flen, last_stream_frame);
+			ret = h3_data_to_htx(qcs, rxbuf, flen, last_stream_frame);
+			/* TODO handle error reporting. Stream closure required. */
+			BUG_ON(ret);
 			break;
 		case H3_FT_HEADERS:
-			h3_headers_to_htx(qcs, rxbuf, flen, last_stream_frame);
+			ret = h3_headers_to_htx(qcs, rxbuf, flen, last_stream_frame);
+			/* TODO handle error reporting. Stream closure required. */
+			BUG_ON(ret);
 			break;
 		case H3_FT_PUSH_PROMISE:
 			/* Not supported */