Coverity warns that the vstream's trace chunk may be used NULL.
However, this won't happen if the corresponding relay stream has
an active trace chunk.
Coverity report:
1433620 Dereference after null check
Either the check against null is unnecessary, or there may be a
null pointer dereference.
In viewer_stream_create: Pointer is checked against null but then
dereferenced anyway (CWE-476)
Reported-by: Coverity Scan
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: Ie032ed415a99cfff149e3325d05f37ededb52d33