diff --git a/src/TestFramework/Coverage/ProxyTrace.php b/src/TestFramework/Coverage/ProxyTrace.php
index c1597df0b..0a60b8d63 100644
--- a/src/TestFramework/Coverage/ProxyTrace.php
+++ b/src/TestFramework/Coverage/ProxyTrace.php
@@ -108,6 +108,10 @@ public function getTests(): ?TestLocations
 
     public function getAllTestsForMutation(NodeLineRangeData $lineRange, bool $isOnFunctionSignature): iterable
     {
+        if ($this->lazyTestLocations === null) {
+            return [];
+        }
+
         return $this->getTestLocator()->getAllTestsForMutation($lineRange, $isOnFunctionSignature);
     }