Log unhandled promise rejection

Author: karlseguin

build.zig.zon

@@ -5,8 +5,8 @@
     .fingerprint = 0xda130f3af836cea0,
     .dependencies = .{
         .v8 = .{
-            .url = "https://github.com/lightpanda-io/zig-v8-fork/archive/e62726800663d0397d8766f7185040d8b8b69402.tar.gz",
-            .hash = "v8-0.0.0-xddH69zDAwD5i0hGhAsv3SPeihlj5fXGpJyO15KqBWOn",
+            .url = "https://github.com/lightpanda-io/zig-v8-fork/archive/efb353230f05c96d5ad96298f8b0b444de615644.tar.gz",
+            .hash = "v8-0.0.0-xddH6xHEAwCo_OGkWshjXdYHGk18oSG3XZPYtf4tvF0P",
         },
         //.v8 = .{ .path = "../zig-v8-fork" }
     },

src/runtime/js.zig

@@ -197,6 +197,7 @@ pub fn Env(comptime State: type, comptime WebApis: type) type {
 
             // This is the callback that runs whenever a module is dynamically imported.
             isolate.setHostImportModuleDynamicallyCallback(JsContext.dynamicModuleCallback);
+            isolate.setPromiseRejectCallback(promiseRejectCallback);
 
             isolate.enter();
             errdefer isolate.exit();
@@ -328,6 +329,20 @@ pub fn Env(comptime State: type, comptime WebApis: type) type {
             self.isolate.lowMemoryNotification();
         }
 
+        fn promiseRejectCallback(v8_msg: v8.C_PromiseRejectMessage) callconv(.c) void {
+            const msg = v8.PromiseRejectMessage.initFromC(v8_msg);
+            const isolate =  msg.getPromise().toObject().getIsolate();
+            const v8_context = isolate.getCurrentContext();
+            const context: *JsContext = @ptrFromInt(v8_context.getEmbedderData(1).castTo(v8.BigInt).getUint64());
+
+            const value =
+                if (msg.getValue()) |v8_value| valueToString(context.call_arena, v8_value, isolate, v8_context) catch |err| @errorName(err)
+                else "no value";
+
+            log.debug(.js, "unhandled rejection", .{.value =value});
+        }
+
+
         // ExecutionWorld closely models a JS World.
         // https://chromium.googlesource.com/chromium/src/+/master/third_party/blink/renderer/bindings/core/v8/V8BindingDesign.md#World
         // https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/API/scripting/ExecutionWorld