Fix -Wunused-but-set-variable in sdk/objc.

Bug: None
Change-Id: I7576db57b0a8d86fe7281176956c2efef78c1252
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/236540
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Kári Helgason <kthelgason@webrtc.org>
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#35273}
diff --git a/sdk/objc/unittests/RTCPeerConnectionTest.mm b/sdk/objc/unittests/RTCPeerConnectionTest.mm
index 1d0ae26..19b3c8e 100644
--- a/sdk/objc/unittests/RTCPeerConnectionTest.mm
+++ b/sdk/objc/unittests/RTCPeerConnectionTest.mm
@@ -128,7 +128,6 @@
   RTC_OBJC_TYPE(RTCPeerConnectionFactory) *factory =
       [[RTC_OBJC_TYPE(RTCPeerConnectionFactory) alloc] init];
 
-  RTC_OBJC_TYPE(RTCConfiguration) * newConfig;
   std::unique_ptr<webrtc::PeerConnectionDependencies> pc_dependencies =
       std::make_unique<webrtc::PeerConnectionDependencies>(nullptr);
   @autoreleasepool {
@@ -137,7 +136,7 @@
                                     constraints:contraints
                                    dependencies:std::move(pc_dependencies)
                                        delegate:nil];
-    newConfig = peerConnection.configuration;
+    ASSERT_NE(peerConnection, nil);
   }
 }