add TryCatch jsutil and use it in socket dialer

cloudflare/sockets/dialer.go

@@ -3,6 +3,7 @@ package sockets
 import (
 	"context"
 	"net"
+	"syscall/js"
 	"time"
 
 	"github.com/syumai/workers/cloudflare/internal/cfruntimecontext"
@@ -42,7 +43,12 @@ func Connect(ctx context.Context, addr string, opts *SocketOptions) (net.Conn, e
 			optionsObj.Set("secureTransport", string(opts.SecureTransport))
 		}
 	}
-	sockVal := connect.Invoke(addr, optionsObj)
+	sockVal, err := jsutil.TryCatch(js.FuncOf(func(_ js.Value, args []js.Value) any {
+		return connect.Invoke(addr, optionsObj)
+	}))
+	if err != nil {
+		return nil, err
+	}
 	deadline := time.Now().Add(defaultDeadline)
 	return newSocket(ctx, sockVal, deadline, deadline), nil
 }

cmd/workers-assets-gen/assets/common/shim.mjs

@@ -5,6 +5,18 @@ const go = new Go();
 
 let mod;
 
+globalThis.tryCatch = (fn) => {
+  try {
+    return {
+      result: fn(),
+    };
+  } catch(e) {
+    return {
+      error: e,
+    }
+  }
+}
+
 export function init(m) {
   mod = m;
 }

internal/jsutil/trycatch.go

@@ -0,0 +1,16 @@
+package jsutil
+
+import (
+	"errors"
+	"syscall/js"
+)
+
+func TryCatch(fn js.Func) (js.Value, error) {
+	fnResultVal := js.Global().Call("tryCatch", fn)
+	resultVal := fnResultVal.Get("result")
+	errorVal := fnResultVal.Get("error")
+	if !errorVal.IsUndefined() {
+		return js.Value{}, errors.New(errorVal.String())
+	}
+	return resultVal, nil
+}