Signaling: Fix possible null access in freeSignaling (#1010)
Signaling: Fix possible null access in freeSignaling (#1010)

Signed-off-by: Alex.Li <3cc4837f158a12569da3fb2429e6e962ae9884f3@amazon.com>
awslabs/amazon-kinesis-video-streams-webrtc-sdk-c,awslabs/amazon-kinesis-video-streams-webrtc-sdk-c,awslabs/amazon-kinesis-video-streams-webrtc-sdk-c,awslabs/amazon-kinesis-video-streams-webrtc-sdk-c