MINOR: quic: Fix potential null pointer dereference

Fix compilation warnings about non initialized pointers.

This partially address #1445 github issue.
diff --git a/src/quic_sock.c b/src/quic_sock.c
index 875779d..bb6cb61 100644
--- a/src/quic_sock.c
+++ b/src/quic_sock.c
@@ -178,7 +178,7 @@
 	struct rxbuf *rxbuf;
 	struct buffer *buf;
 	struct listener *l = objt_listener(fdtab[fd].owner);
-	struct quic_transport_params *params = &l->bind_conf->quic_params;
+	struct quic_transport_params *params;
 	/* Source address */
 	struct sockaddr_storage saddr = {0};
 	size_t max_sz;
@@ -186,11 +186,18 @@
 
 	BUG_ON(!l);
 
+	if (!l)
+		return;
+
 	if (!(fdtab[fd].state & FD_POLL_IN) || !fd_recv_ready(fd))
 		return;
 
 	rxbuf = MT_LIST_POP(&l->rx.rxbuf_list, typeof(rxbuf), mt_list);
 	buf = &rxbuf->buf;
+	if (!buf)
+		goto out;
+
+	params = &l->bind_conf->quic_params;
 	max_sz = params->max_udp_payload_size;
 	if (b_contig_space(buf) < max_sz) {
 		/* Note that when we enter this function, <buf> is always empty */
diff --git a/src/xprt_quic.c b/src/xprt_quic.c
index 09722c0..0fdc7aa 100644
--- a/src/xprt_quic.c
+++ b/src/xprt_quic.c
@@ -3309,6 +3309,7 @@
 	struct quic_enc_level *qel;
 
 	qc = NULL;
+	qel = NULL;
 	TRACE_ENTER(QUIC_EV_CONN_SPKT);
 	if (end <= *buf)
 		goto err;
@@ -3461,6 +3462,7 @@
 
 	qc = NULL;
 	conn_ctx = NULL;
+	qel = NULL;
 	TRACE_ENTER(QUIC_EV_CONN_LPKT, NULL, pkt);
 	if (end <= *buf)
 		goto err;