[cleanup] Provide better error message if the snapshot blob is missing

R=yangguo@chromium.org

Bug: chromium:872783, v8:8015
Cq-Include-Trybots: luci.chromium.try:linux_chromium_rel_ng
Change-Id: I2d281ba058961ebe2e2758e90b4afa34b02fd5b1
Reviewed-on: https://chromium-review.googlesource.com/1216004Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56197}

src/api.cc

@@ -8212,7 +8212,11 @@ void Isolate::Initialize(Isolate* isolate,
   if (params.entry_hook || !i::Snapshot::Initialize(i_isolate)) {
     // If snapshot data was provided and we failed to deserialize it must
     // have been corrupted.
-    CHECK_NULL(i_isolate->snapshot_blob());
+    if (i_isolate->snapshot_blob() != nullptr) {
+      FATAL(
+          "Failed to deserialize the V8 snapshot blob. This can mean that the "
+          "snapshot blob file is corrupted or missing.");
+    }
     base::ElapsedTimer timer;
     if (i::FLAG_profile_deserialization) timer.Start();
     i_isolate->Init(nullptr);