Fix NPE when collecting network metrics.

PiperOrigin-RevId: 684778774
Change-Id: I5574a8d506b65e398108c8ca58b8045a720f8a8c

src/main/java/com/google/devtools/build/lib/profiler/CollectLocalResourceUsage.java

diff --git a/src/main/java/com/google/devtools/build/lib/profiler/CollectLocalResourceUsage.java b/src/main/java/com/google/devtools/build/lib/profiler/CollectLocalResourceUsage.java
index 618870b..48cec24 100644
--- a/src/main/java/com/google/devtools/build/lib/profiler/CollectLocalResourceUsage.java
+++ b/src/main/java/com/google/devtools/build/lib/profiler/CollectLocalResourceUsage.java
@@ -430,8 +430,10 @@
     public void collect(double deltaNanos, BiConsumer<CounterSeriesTask, Double> consumer) {
       var systemNetworkUsages =
           NetworkMetricsCollector.instance().collectSystemNetworkUsages(deltaNanos);
-      consumer.accept(SYSTEM_NETWORK_UP_USAGE, systemNetworkUsages.megabitsSentPerSec());
-      consumer.accept(SYSTEM_NETWORK_DOWN_USAGE, systemNetworkUsages.megabitsRecvPerSec());
+      if (systemNetworkUsages != null) {
+        consumer.accept(SYSTEM_NETWORK_UP_USAGE, systemNetworkUsages.megabitsSentPerSec());
+        consumer.accept(SYSTEM_NETWORK_DOWN_USAGE, systemNetworkUsages.megabitsRecvPerSec());
+      }
     }
   }