Don't crash if createDataChannel fails.
Don't crash if createDataChannel fails.

It can fail in some real circumstances, such as when IDs are exhausted
or you explicitly try to create one with an already-used ID.

Review-Url: https://codereview.webrtc.org/2181933002
Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#13535}

ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,TimothyGu/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc