fix: add more helpful error messages when fMP is missing (#1959)

GoogleChrome · Apr 4, 2017 · 0bf1744 · 0bf1744
1 parent 2d330c8
commit 0bf1744
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diff --git a/lighthouse-core/audits/estimated-input-latency.js b/lighthouse-core/audits/estimated-input-latency.js
@@ -46,6 +46,9 @@ class EstimatedInputLatency extends Audit {
 
   static calculate(tabTrace, model, trace) {
     const startTime = tabTrace.timings.firstMeaningfulPaint;
+    if (!startTime) {
+      throw new Error('No firstMeaningfulPaint event found in trace');
+    }
 
     const latencyPercentiles = TracingProcessor.getRiskToResponsiveness(model, trace, startTime);
     const ninetieth = latencyPercentiles.find(result => result.percentile === 0.9);

diff --git a/lighthouse-core/audits/time-to-interactive.js b/lighthouse-core/audits/time-to-interactive.js
@@ -170,6 +170,10 @@ class TTIMetric extends Audit {
       const fMPtsInMS = tabTrace.timestamps.firstMeaningfulPaint;
       const navStartTsInMS = tabTrace.timestamps.navigationStart;
 
+      if (!fMPtsInMS) {
+        throw new Error('No firstMeaningfulPaint event found in trace');
+      }
+
       const fmpTiming = tabTrace.timings.firstMeaningfulPaint;
       const traceEndTiming = tabTrace.timings.traceEnd;