Deduplicate success log in JsonRpcClient.invoke

Log success once after deserialization (or null for Void) rather than
duplicating the logTiming call in both branches.

Co-authored-by: edburns <75821+edburns@users.noreply.github.com>

Author: Copilot

src/main/java/com/github/copilot/sdk/JsonRpcClient.java

@@ -124,14 +124,10 @@ public <T> CompletableFuture<T> invoke(String method, Object params, Class<T> re
 
         return future.thenApply(result -> {
             try {
-                if (responseType == Void.class || responseType == void.class) {
-                    LoggingHelpers.logTiming(LOG, Level.FINE,
-                            "JsonRpc.invoke JSON-RPC request finished. Elapsed={Elapsed}, Method=" + method
-                                    + ", RequestId=" + id + ", Status=Succeeded",
-                            timingNanos);
-                    return null;
+                T value = null;
+                if (responseType != Void.class && responseType != void.class) {
+                    value = MAPPER.treeToValue(result, responseType);
                 }
-                T value = MAPPER.treeToValue(result, responseType);
                 LoggingHelpers.logTiming(LOG, Level.FINE,
                         "JsonRpc.invoke JSON-RPC request finished. Elapsed={Elapsed}, Method=" + method + ", RequestId="
                                 + id + ", Status=Succeeded",