Bluetooth: audio: has: Fix coverity issues

This fixes issues discovered by coverity check.

Fixes: #65325
Fixes: #65326
Signed-off-by: Mariusz Skamra <mariusz.skamra@codecoup.pl>
diff --git a/subsys/bluetooth/audio/has.c b/subsys/bluetooth/audio/has.c
index 6013cad..26f719b 100644
--- a/subsys/bluetooth/audio/has.c
+++ b/subsys/bluetooth/audio/has.c
@@ -205,6 +205,8 @@
 
 static struct client_context *context_find(const bt_addr_le_t *addr)
 {
+	__ASSERT_NO_MSG(addr != NULL);
+
 	for (size_t i = 0; i < ARRAY_SIZE(contexts); i++) {
 		if (bt_addr_le_eq(&contexts[i].addr, addr)) {
 			return &contexts[i];
@@ -218,6 +220,8 @@
 {
 	struct client_context *context;
 
+	__ASSERT_NO_MSG(addr != NULL);
+
 	/* Free contexts has BT_ADDR_LE_ANY as the address */
 	context = context_find(BT_ADDR_LE_ANY);
 	if (context == NULL) {
@@ -262,6 +266,7 @@
 {
 	struct bt_conn_info info = { 0 };
 	struct has_client *client = NULL;
+	int err;
 
 	for (size_t i = 0; i < ARRAY_SIZE(has_client_list); i++) {
 		if (conn == has_client_list[i].conn) {
@@ -284,7 +289,12 @@
 	k_work_init_delayable(&client->notify_work, notify_work_handler);
 #endif /* CONFIG_BT_HAS_PRESET_SUPPORT || CONFIG_BT_HAS_FEATURES_NOTIFIABLE */
 
-	bt_conn_get_info(conn, &info);
+	err = bt_conn_get_info(conn, &info);
+	if (err != 0) {
+		LOG_DBG("Could not get conn info: %d", err);
+
+		return NULL;
+	}
 
 	client->context = context_find(info.le.dst);
 	if (client->context == NULL) {