gh-154089: Hide unavailable replay efficiency (#154092)

Lib/profiling/sampling/_flamegraph_assets/flamegraph.js

diff --git a/Lib/profiling/sampling/_flamegraph_assets/flamegraph.js b/Lib/profiling/sampling/_flamegraph_assets/flamegraph.js
index e055801..d66da04 100644
--- a/Lib/profiling/sampling/_flamegraph_assets/flamegraph.js
+++ b/Lib/profiling/sampling/_flamegraph_assets/flamegraph.js
@@ -955,8 +955,8 @@
     : (stats.total_samples ?? data.value ?? 0);
   const duration = stats.duration_sec || 0;
   const sampleRate = stats.sample_rate || (duration > 0 ? totalSamples / duration : 0);
-  const errorRate = stats.error_rate || 0;
-  const missedSamples= stats.missed_samples || 0;
+  const errorRate = stats.error_rate;
+  const missedSamples = stats.missed_samples;
 
   const samplesEl = document.getElementById('stat-total-samples');
   if (samplesEl) samplesEl.textContent = formatNumber(totalSamples);

Misc/NEWS.d/next/Library/2026-07-19-11-20-00.gh-issue-154089.Vp2qHx.rst

diff --git a/Misc/NEWS.d/next/Library/2026-07-19-11-20-00.gh-issue-154089.Vp2qHx.rst b/Misc/NEWS.d/next/Library/2026-07-19-11-20-00.gh-issue-154089.Vp2qHx.rst
new file mode 100644
index 0000000..ba6ec43
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2026-07-19-11-20-00.gh-issue-154089.Vp2qHx.rst
@@ -0,0 +1,2 @@
+Do not show unavailable sampling efficiency statistics in replayed Tachyon
+flamegraphs.