We hit a fuzzer bug that caused numDecodedBytesLB + numDecodedBytesUB > lenEncodedBytes, which is obviously bogus. Check for that, and for the case whhere the UB decoder itself realized that something was wrong. (The code already makes the corresponding check for the LB decoder.) BUG=chromium:637899 Review-Url: https://codereview.webrtc.org/2315693002 Cr-Commit-Position: refs/heads/master@{#14091}