[LLDB][NFC] Refactor code extracting timestamp from StructuredData (#145954)

Co-authored-by: Alex Langford <nirvashtzero@gmail.com>

Author: oontvoo

lldb/source/Core/Telemetry.cpp

@@ -119,6 +119,19 @@ llvm::Error TelemetryManager::preDispatch(TelemetryInfo *entry) {
   return llvm::Error::success();
 }
 
+// Helper for extracting time field from a Dictionary.
+static std::optional<std::chrono::nanoseconds>
+GetAsNanosec(StructuredData::Dictionary *dict, llvm::StringRef key) {
+  auto value = dict->GetValueForKey(key);
+  if (!value->IsValid()) {
+    LLDB_LOG(GetLog(LLDBLog::Object),
+             "Cannot determine {0} from client-telemetry entry", key);
+    return std::nullopt;
+  }
+
+  return std::chrono::nanoseconds(value->GetUnsignedIntegerValue(0));
+}
+
 void TelemetryManager::DispatchClientTelemetry(
     const lldb_private::StructuredDataImpl &entry, Debugger *debugger) {
   if (!m_config->enable_client_telemetry)
@@ -148,23 +161,12 @@ void TelemetryManager::DispatchClientTelemetry(
     LLDB_LOG(GetLog(LLDBLog::Object),
              "Cannot determine client_data from client-telemetry entry");
 
-  int64_t start_time;
-  if (dict->GetValueForKeyAsInteger("start_time", start_time)) {
-    client_info.start_time +=
-        std::chrono::nanoseconds(static_cast<size_t>(start_time));
-  } else {
-    LLDB_LOG(GetLog(LLDBLog::Object),
-             "Cannot determine start-time from client-telemetry entry");
-  }
+  if (auto maybe_start_time = GetAsNanosec(dict, "start_time"))
+    client_info.start_time += *maybe_start_time;
 
-  int64_t end_time;
-  if (dict->GetValueForKeyAsInteger("end_time", end_time)) {
+  if (auto maybe_end_time = GetAsNanosec(dict, "end_time")) {
     SteadyTimePoint epoch;
-    client_info.end_time =
-        epoch + std::chrono::nanoseconds(static_cast<size_t>(end_time));
-  } else {
-    LLDB_LOG(GetLog(LLDBLog::Object),
-             "Cannot determine end-time from client-telemetry entry");
+    client_info.end_time = epoch + *maybe_end_time;
   }
 
   llvm::StringRef error_msg;