3 files changed, 30 insertions, 21 deletions

diff --git a/src/buildtool/execution_engine/dag/dag.cpp b/src/buildtool/execution_engine/dag/dag.cpp
index 17f4b3af..cb82ec55 100644
--- a/src/buildtool/execution_engine/dag/dag.cpp
+++ b/src/buildtool/execution_engine/dag/dag.cpp
@@ -148,7 +148,7 @@ auto DependencyGraph::AddAction(ActionDescription const& description) -> bool {
 
 auto DependencyGraph::AddAction(Action const& a) noexcept
     -> DependencyGraph::ActionNodeIdentifier {
-    auto id = a.Id();
+    auto const& id = a.Id();
     auto const action_it = action_ids_.find(id);
     if (action_it != action_ids_.end()) {
         return action_it->second;
diff --git a/src/buildtool/execution_engine/dag/dag.hpp b/src/buildtool/execution_engine/dag/dag.hpp
index 99a35f4b..7e2194ff 100644
--- a/src/buildtool/execution_engine/dag/dag.hpp
+++ b/src/buildtool/execution_engine/dag/dag.hpp
@@ -314,57 +314,60 @@ class DependencyGraph : DirectedAcyclicGraph {
             return true;
         }
 
-        [[nodiscard]] auto OutputFiles()
-            const& -> std::vector<NamedOtherNodePtr> const& {
+        [[nodiscard]] auto OutputFiles() const& noexcept
+            -> std::vector<NamedOtherNodePtr> const& {
             return output_files_;
         }
 
-        [[nodiscard]] auto OutputDirs()
-            const& -> std::vector<NamedOtherNodePtr> const& {
+        [[nodiscard]] auto OutputDirs() const& noexcept
+            -> std::vector<NamedOtherNodePtr> const& {
             return output_dirs_;
         }
 
-        [[nodiscard]] auto Dependencies()
-            const& -> std::vector<NamedOtherNodePtr> const& {
+        [[nodiscard]] auto Dependencies() const& noexcept
+            -> std::vector<NamedOtherNodePtr> const& {
             return dependencies_;
         }
 
-        [[nodiscard]] auto Command() const -> std::vector<std::string> {
+        [[nodiscard]] auto Command() const noexcept
+            -> std::vector<std::string> const& {
             return Content().Command();
         }
 
-        [[nodiscard]] auto Env() const -> std::map<std::string, std::string> {
+        [[nodiscard]] auto Env() const noexcept
+            -> std::map<std::string, std::string> const& {
             return Content().Env();
         }
 
-        [[nodiscard]] auto MayFail() const -> std::optional<std::string> {
+        [[nodiscard]] auto MayFail() const noexcept
+            -> std::optional<std::string> const& {
             return Content().MayFail();
         }
 
-        [[nodiscard]] auto TimeoutScale() const -> double {
+        [[nodiscard]] auto TimeoutScale() const noexcept -> double {
             return Content().TimeoutScale();
         }
 
-        [[nodiscard]] auto ExecutionProperties() const
-            -> std::map<std::string, std::string> {
+        [[nodiscard]] auto ExecutionProperties() const noexcept
+            -> std::map<std::string, std::string> const& {
             return Content().ExecutionProperties();
         }
 
-        [[nodiscard]] auto NoCache() const -> bool {
+        [[nodiscard]] auto NoCache() const noexcept -> bool {
             return Content().NoCache();
         }
 
-        [[nodiscard]] auto OutputFilePaths() const
+        [[nodiscard]] auto OutputFilePaths() const noexcept
             -> std::vector<Action::LocalPath> {
             return NodePaths(output_files_);
         }
 
-        [[nodiscard]] auto OutputDirPaths() const
+        [[nodiscard]] auto OutputDirPaths() const noexcept
             -> std::vector<Action::LocalPath> {
             return NodePaths(output_dirs_);
         }
 
-        [[nodiscard]] auto DependencyPaths() const
+        [[nodiscard]] auto DependencyPaths() const noexcept
             -> std::vector<Action::LocalPath> {
             return NodePaths(dependencies_);
         }
diff --git a/src/buildtool/execution_engine/executor/executor.hpp b/src/buildtool/execution_engine/executor/executor.hpp
index d0bc7aee..097284e1 100644
--- a/src/buildtool/execution_engine/executor/executor.hpp
+++ b/src/buildtool/execution_engine/executor/executor.hpp
@@ -972,11 +972,17 @@ class Rebuilder {
                 return artifacts_cached.error();
             }
             std::ostringstream msg{};
-            for (auto const& [path, info] : *artifacts.value()) {
-                auto const& info_cached = artifacts_cached.value()->at(path);
-                if (info != info_cached) {
-                    RecordFlakyAction(&msg, action, path, info, info_cached);
+            try {
+                for (auto const& [path, info] : *artifacts.value()) {
+                    auto const& info_cached =
+                        artifacts_cached.value()->at(path);
+                    if (info != info_cached) {
+                        RecordFlakyAction(
+                            &msg, action, path, info, info_cached);
+                    }
                 }
+            } catch (std::exception const& ex) {
+                return ex.what();
             }
             if (msg.tellp() > 0) {
                 stats.IncrementActionsFlakyCounter();