NetEq: Don't check sample rate and frame size upon error

If an error happens in the GetAudio call, for instance when corrupt
payloads are inserted, GetAudio wil return an error. In this case, the
audio frame is not always correctly populated, which is to be expected.

BUG=webrtc:5447

Review-Url: https://codereview.webrtc.org/2272963002
Cr-Commit-Position: refs/heads/master@{#13902}
diff --git a/webrtc/modules/audio_coding/neteq/neteq_impl.cc b/webrtc/modules/audio_coding/neteq/neteq_impl.cc
index 9cd73b6..e65466f 100644
--- a/webrtc/modules/audio_coding/neteq/neteq_impl.cc
+++ b/webrtc/modules/audio_coding/neteq/neteq_impl.cc
@@ -206,13 +206,13 @@
   TRACE_EVENT0("webrtc", "NetEqImpl::GetAudio");
   rtc::CritScope lock(&crit_sect_);
   int error = GetAudioInternal(audio_frame, muted);
-  RTC_DCHECK_EQ(
-      audio_frame->sample_rate_hz_,
-      rtc::checked_cast<int>(audio_frame->samples_per_channel_ * 100));
   if (error != 0) {
     error_code_ = error;
     return kFail;
   }
+  RTC_DCHECK_EQ(
+      audio_frame->sample_rate_hz_,
+      rtc::checked_cast<int>(audio_frame->samples_per_channel_ * 100));
   SetAudioFrameActivityAndType(vad_->enabled(), LastOutputType(),
                                last_vad_activity_, audio_frame);
   last_vad_activity_ = audio_frame->vad_activity_;