fix: less flakey scans when using multiple samples

Fixes #60

packages/core/src/puppeteer/tasks/lighthouse.ts

@@ -139,18 +139,11 @@ export const runLighthouseTask: PuppeteerTask = async (props) => {
   }
 
   let report: LH.Result = samples[0]
-  if (samples.length > 1) {
-    try {
-      report = computeMedianRun(samples)
-    }
-    catch (e) {
-      logger.warn('Error when computing median score, possibly audit failed.', e)
-    }
-  }
 
   if (!report) {
     logger.error(`Task \`runLighthouseTask\` has failed to run for path "${routeReport.route.path}".`)
     routeReport.tasks.runLighthouseTask = 'failed'
+    return routeReport
   }
 
   if (report.categories.performance && !report.categories.performance.score) {
@@ -159,6 +152,15 @@ export const runLighthouseTask: PuppeteerTask = async (props) => {
     return routeReport
   }
 
+  if (samples.length > 1) {
+    try {
+      report = computeMedianRun(samples)
+    }
+    catch (e) {
+      logger.warn('Error when computing median score, possibly audit failed.', e)
+    }
+  }
+
   // we need to export all base64 data to improve the stability of the client
   if (report.audits?.['final-screenshot']?.details?.data)
     await fs.writeFile(join(routeReport.artifactPath, ReportArtifacts.screenshot), base64ToBuffer(report.audits['final-screenshot'].details.data))