Respond to CR.

Signal/src/call/CallService.swift

@@ -408,10 +408,10 @@ private class SignalCallData: NSObject {
             }
 
             return peerConnectionClient.setLocalSessionDescription(sessionDescription).then {
+                do {
                     let offerBuilder = SSKProtoCallMessageOffer.SSKProtoCallMessageOfferBuilder()
                     offerBuilder.setId(call.signalingId)
                     offerBuilder.setSessionDescription(sessionDescription.sdp)
-                do {
                     let offer = try offerBuilder.build()
                     let callMessage = OWSOutgoingCallMessage(thread: call.thread, offerMessage: offer)
                     return self.messageSender.sendPromise(message: callMessage)
@@ -719,10 +719,10 @@ private class SignalCallData: NSObject {
                 throw CallError.obsoleteCall(description: "negotiateSessionDescription() response for obsolete call")
             }
 
+            do {
                 let answerBuilder = SSKProtoCallMessageAnswer.SSKProtoCallMessageAnswerBuilder()
                 answerBuilder.setId(newCall.signalingId)
                 answerBuilder.setSessionDescription(negotiatedSessionDescription.sdp)
-            do {
                 let answer = try answerBuilder.build()
                 let callAnswerMessage = OWSOutgoingCallMessage(thread: thread, answerMessage: answer)
 
@@ -860,17 +860,17 @@ private class SignalCallData: NSObject {
 
             Logger.info("\(self.logTag) in \(#function) sending ICE Candidate \(call.identifiersForLogs).")
 
+            do {
                 /**
                  * Sent by both parties out of band of the RTC calling channels, as part of setting up those channels. The messages
                  * include network accessibility information from the perspective of each client. Once compatible ICEUpdates have been
-             * exchanged, the clients can connect directly.
+                 * exchanged, the clients can connect.
                  */
                 let iceUpdateBuilder = SSKProtoCallMessageIceUpdate.SSKProtoCallMessageIceUpdateBuilder()
                 iceUpdateBuilder.setId(call.signalingId)
                 iceUpdateBuilder.setSdp(iceCandidate.sdp)
                 iceUpdateBuilder.setSdpMlineIndex(UInt32(iceCandidate.sdpMLineIndex))
                 iceUpdateBuilder.setSdpMid(sdpMid)
-            do {
                 let iceUpdate = try iceUpdateBuilder.build()
 
                 let callMessage = OWSOutgoingCallMessage(thread: call.thread, iceUpdateMessage: iceUpdate)
@@ -1208,7 +1208,6 @@ private class SignalCallData: NSObject {
         }
 
         // If the call hasn't started yet, we don't have a data channel to communicate the hang up. Use Signal Service Message.
-
         do {
             let hangupBuilder = SSKProtoCallMessageHangup.SSKProtoCallMessageHangupBuilder()
             hangupBuilder.setId(call.signalingId)