[#6102] fixed JSVM exception -> Go error unwrapping

plugins/jsvm/binds.go

@@ -81,14 +81,14 @@ func hooksBinds(app core.App, loader *goja.Runtime, executors *vmsPool) {
 					res, err := executor.RunProgram(pr)
 					executor.Set("__args", goja.Undefined())
 
-					// check for returned error value
+					// (legacy) check for returned Go error value
 					if res != nil {
 						if resErr, ok := res.Export().(error); ok {
 							return resErr
 						}
 					}
 
-					return err
+					return normalizeException(err)
 				})
 
 				return []reflect.Value{reflect.ValueOf(&err).Elem()}
@@ -197,14 +197,14 @@ func wrapHandlerFunc(executors *vmsPool, handler goja.Value) (func(*core.Request
 				res, err := executor.RunProgram(pr)
 				executor.Set("__args", goja.Undefined())
 
-				// check for returned error
+				// (legacy) check for returned Go error value
 				if res != nil {
 					if v, ok := res.Export().(error); ok {
 						return v
 					}
 				}
 
-				return err
+				return normalizeException(err)
 			})
 		}
 
@@ -215,9 +215,9 @@ func wrapHandlerFunc(executors *vmsPool, handler goja.Value) (func(*core.Request
 }
 
 type gojaHookHandler struct {
-	priority       int
 	id             string
 	serializedFunc string
+	priority       int
 }
 
 func wrapMiddlewares(executors *vmsPool, rawMiddlewares ...goja.Value) ([]*hook.Handler[*core.RequestEvent], error) {
@@ -254,14 +254,14 @@ func wrapMiddlewares(executors *vmsPool, rawMiddlewares ...goja.Value) ([]*hook.
 						res, err := executor.RunProgram(pr)
 						executor.Set("__args", goja.Undefined())
 
-						// check for returned error
+						// (legacy) check for returned Go error value
 						if res != nil {
 							if v, ok := res.Export().(error); ok {
 								return v
 							}
 						}
 
-						return err
+						return normalizeException(err)
 					})
 				},
 			}
@@ -276,14 +276,14 @@ func wrapMiddlewares(executors *vmsPool, rawMiddlewares ...goja.Value) ([]*hook.
 						res, err := executor.RunProgram(pr)
 						executor.Set("__args", goja.Undefined())
 
-						// check for returned error
+						// (legacy) check for returned Go error value
 						if res != nil {
 							if v, ok := res.Export().(error); ok {
 								return v
 							}
 						}
 
-						return err
+						return normalizeException(err)
 					})
 				},
 			}
@@ -1019,3 +1019,29 @@ func newDynamicModel(shape map[string]any) any {
 
 	return elem.Addr().Interface()
 }
+
+// normalizeException checks if the provided error is a goja.Exception
+// and attempts to return its underlying Go error.
+//
+// note: using just goja.Exception.Unwrap() is insufficient and may falsely result in nil.
+func normalizeException(err error) error {
+	if err == nil {
+		return nil
+	}
+
+	jsException, ok := err.(*goja.Exception)
+	if !ok {
+		return err // no exception
+	}
+
+	switch v := jsException.Value().Export().(type) {
+	case error:
+		err = v
+	case map[string]any: // goja.GoError
+		if vErr, ok := v["value"].(error); ok {
+			err = vErr
+		}
+	}
+
+	return err
+}

plugins/jsvm/binds_test.go

@@ -2,6 +2,7 @@ package jsvm
 
 import (
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"mime/multipart"
@@ -1456,6 +1457,47 @@ func TestHooksBinds(t *testing.T) {
 	}
 }
 
+func TestHooksExceptionUnwrapping(t *testing.T) {
+	app, _ := tests.NewTestApp()
+	defer app.Cleanup()
+
+	goErr := errors.New("test")
+
+	vmFactory := func() *goja.Runtime {
+		vm := goja.New()
+		baseBinds(vm)
+		vm.Set("$app", app)
+		vm.Set("goErr", goErr)
+		return vm
+	}
+
+	pool := newPool(1, vmFactory)
+
+	vm := vmFactory()
+	hooksBinds(app, vm, pool)
+
+	_, err := vm.RunString(`
+		onModelUpdate((e) => {
+			throw goErr
+		}, "demo1")
+	`)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	record, err := app.FindFirstRecordByFilter("demo1", "1=1")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	record.Set("text", "update")
+
+	err = app.Save(record)
+	if !errors.Is(err, goErr) {
+		t.Fatalf("Expected goError, got %v", err)
+	}
+}
+
 func TestRouterBindsCount(t *testing.T) {
 	app, _ := tests.NewTestApp()
 	defer app.Cleanup()

plugins/jsvm/jsvm.go

@@ -326,21 +326,7 @@ func (p *plugin) normalizeServeExceptions(e *core.RequestEvent) error {
 		return err // no error or already committed
 	}
 
-	jsException, ok := err.(*goja.Exception)
-	if !ok {
-		return err // no exception
-	}
-
-	switch v := jsException.Value().Export().(type) {
-	case error:
-		err = v
-	case map[string]any: // goja.GoError
-		if vErr, ok := v["value"].(error); ok {
-			err = vErr
-		}
-	}
-
-	return err
+	return normalizeException(err)
 }
 
 // watchHooks initializes a hooks file watcher that will restart the