Print backtrace if runner panics

errors.go

@@ -42,3 +42,12 @@ var (
 	// ErrNotAnInterface is returned when a type is not an interface.
 	ErrNotAnInterface = errors.New("not an interface")
 )
+
+type PanicError struct {
+	error
+	backtrace string
+}
+
+func (e *PanicError) Backtrace() string {
+	return e.backtrace
+}

services.go

@@ -2,6 +2,7 @@ package pal
 
 import (
 	"context"
+	"fmt"
 )
 
 func runService(ctx context.Context, name string, instance any, p *Pal) error {
@@ -11,7 +12,7 @@ func runService(ctx context.Context, name string, instance any, p *Pal) error {
 		return nil
 	}
 
-	return tryWrap(func() error {
+	err := tryWrap(func() error {
 		logger.Debug("Running")
 		err := runner.Run(ctx)
 		if err != nil {
@@ -22,6 +23,14 @@ func runService(ctx context.Context, name string, instance any, p *Pal) error {
 		logger.Debug("Runner finished successfully")
 		return nil
 	})()
+
+	if err != nil {
+		if panicErr, ok := err.(*PanicError); ok {
+			fmt.Printf("panic: %s\n%s\n", panicErr.Error(), panicErr.Backtrace())
+		}
+	}
+
+	return err
 }
 
 func healthcheckService[T any](ctx context.Context, name string, instance T, hook LifecycleHook[T], p *Pal) error {

utils.go

@@ -3,6 +3,8 @@ package pal
 import (
 	"fmt"
 	"reflect"
+	"runtime"
+	"strings"
 )
 
 func empty[T any]() T {
@@ -25,9 +27,36 @@ func tryWrap(f func() error) func() error {
 				default:
 					err = fmt.Errorf("%v", x)
 				}
+
+				err = &PanicError{
+					error:     err,
+					backtrace: backtrace(4),
+				}
 			}
 		}()
 		err = f()
 		return
 	}
 }
+
+func backtrace(skipLastN int) string {
+	pc := make([]uintptr, 100)
+	n := runtime.Callers(skipLastN, pc)
+
+	pc = pc[:n]
+
+	var stackTrace strings.Builder
+
+	frames := runtime.CallersFrames(pc)
+
+	for {
+		frame, more := frames.Next()
+		stackTrace.WriteString(fmt.Sprintf("%s\n\t%s:%d\n", frame.Function, frame.File, frame.Line))
+
+		if !more {
+			break
+		}
+	}
+
+	return stackTrace.String()
+}