diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 595f496e1d..23aa1f21de 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -746,8 +746,30 @@ jobs:
           docker run --rm -i -v "$PWD:/scripts" -w /scripts ${{ env.IMAGE }}:after php <<'PHP' > benchmark-comment.txt
           <?php
 
-          $before = json_decode(file_get_contents('benchmark-before-summary.json'), true);
-          $after = json_decode(file_get_contents('benchmark-after-summary.json'), true);
+          function read_summary(string $path): array
+          {
+              if (!is_file($path)) {
+                  fwrite(STDERR, "Missing benchmark summary: {$path}\n");
+                  exit(1);
+              }
+
+              try {
+                  $summary = json_decode(file_get_contents($path), true, 512, JSON_THROW_ON_ERROR);
+              } catch (JsonException $error) {
+                  fwrite(STDERR, "Invalid benchmark summary {$path}: {$error->getMessage()}\n");
+                  exit(1);
+              }
+
+              if (!is_array($summary)) {
+                  fwrite(STDERR, "Invalid benchmark summary {$path}: expected JSON object\n");
+                  exit(1);
+              }
+
+              return $summary;
+          }
+
+          $before = read_summary('benchmark-before-summary.json');
+          $after = read_summary('benchmark-after-summary.json');
 
           function metric_value(?array $data, string $metric, string $stat): mixed
           {
diff --git a/tests/benchmarks/http.php b/tests/benchmarks/http.php
index 3d7556e8d7..1c28ef33ea 100644
--- a/tests/benchmarks/http.php
+++ b/tests/benchmarks/http.php
@@ -290,7 +290,12 @@ final class HttpBenchmark
             $context = $this->setup();
 
             for ($i = 0; $i < $this->iterations * $this->vus; $i++) {
-                $this->curatedFlows($context);
+                try {
+                    $this->curatedFlows($context);
+                } catch (Throwable $error) {
+                    $exitCode = 1;
+                    fwrite(STDERR, 'Iteration ' . ($i + 1) . ' failed: ' . $error->getMessage() . PHP_EOL);
+                }
             }
         } catch (Throwable $error) {
             $exitCode = 1;
@@ -1216,7 +1221,7 @@ final class HttpBenchmark
             '',
         ];
 
-        return implode(PHP_EOL, array_filter($lines, fn (string $line): bool => $line !== '')) . PHP_EOL;
+        return implode(PHP_EOL, $lines) . PHP_EOL;
     }
 
     private function comparisonTable(?array $before, array $after): string