bootstrap: mksnapshot should show JS error

PR-URL: https://github.com/nodejs/node/pull/38174
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: James M Snell <jasnell@gmail.com>

1 files changed, 41 insertions, 0 deletions

diff --git a/tools/snapshot/snapshot_builder.cc b/tools/snapshot/snapshot_builder.cc
index f97c646dfa1..e259604194b 100644
--- a/tools/snapshot/snapshot_builder.cc
+++ b/tools/snapshot/snapshot_builder.cc
@@ -15,8 +15,12 @@ using v8::Context;
 using v8::HandleScope;
 using v8::Isolate;
 using v8::Local;
+using v8::Object;
 using v8::SnapshotCreator;
 using v8::StartupData;
+using v8::String;
+using v8::TryCatch;
+using v8::Value;
 
 template <typename T>
 void WriteVector(std::stringstream* ss, const T* vec, size_t size) {
@@ -79,6 +83,10 @@ std::string SnapshotBuilder::Generate(
     const std::vector<std::string> args,
     const std::vector<std::string> exec_args) {
   Isolate* isolate = Isolate::Allocate();
+  isolate->SetCaptureStackTraceForUncaughtExceptions(
+    true,
+    10,
+    v8::StackTrace::StackTraceOptions::kDetailed);
   per_process::v8_platform.Platform()->RegisterIsolate(isolate,
                                                        uv_default_loop());
   std::unique_ptr<NodeMainInstance> main_instance;
@@ -104,7 +112,40 @@ std::string SnapshotBuilder::Generate(
       creator.SetDefaultContext(Context::New(isolate));
       isolate_data_indexes = main_instance->isolate_data()->Serialize(&creator);
 
+      TryCatch bootstrapCatch(isolate);
       Local<Context> context = NewContext(isolate);
+      if (bootstrapCatch.HasCaught()) {
+        Local<Object> obj = bootstrapCatch.Exception()->ToObject(context)
+            .ToLocalChecked();
+        Local<Value> stack = obj->Get(
+            context,
+            FIXED_ONE_BYTE_STRING(isolate, "stack")).ToLocalChecked();
+        if (stack->IsUndefined()) {
+          Local<String> str = obj->Get(
+              context,
+              FIXED_ONE_BYTE_STRING(isolate, "name"))
+            .ToLocalChecked()->ToString(context).ToLocalChecked();
+          str = String::Concat(
+            isolate,
+            str,
+            FIXED_ONE_BYTE_STRING(isolate, ": "));
+          stack = String::Concat(
+            isolate,
+            str,
+            obj->Get(
+                context,
+                FIXED_ONE_BYTE_STRING(isolate, "message"))
+              .ToLocalChecked()->ToString(context).ToLocalChecked());
+        }
+        v8::String::Utf8Value utf8_value(isolate, stack);
+        if (*utf8_value != nullptr) {
+          std::string out(*utf8_value, utf8_value.length());
+          fprintf(stderr, "Had Exception: %s\n", out.c_str());
+        } else {
+          fprintf(stderr, "Unknown JS Exception\n");
+        }
+        abort();
+      }
       Context::Scope context_scope(context);
 
       env = new Environment(main_instance->isolate_data(),