stream: Assert that fd is valid in stream_cli_handle_connecting()

This function should never be called if we don't have a valid fd.

Change-Id: If0bed2bae556e0a8233e9e66e82c70a5c677fc3c
Fixes: Coverity CID#321045
---
M src/stream.c
1 file changed, 13 insertions(+), 0 deletions(-)

diff --git a/src/stream.c b/src/stream.c
index 2ba4cde..31aa058 100644
--- a/src/stream.c
+++ b/src/stream.c
@@ -480,6 +480,7 @@
 	socklen_t len = sizeof(error);
 
 	int fd = osmo_stream_cli_fd(cli);
+	OSMO_ASSERT(fd >= 0);
 
 	if (ret < 0) {
 		osmo_stream_cli_reconnect(cli);

