When calling Render with a layout and a nil binding: panic: assignment to entry in nil map

[flowonyx]

The issue is that in jetVarMap it assumes that a nil binding should result in a nil jet.VarMap.

template/jet/jet.go

Lines 233 to 237 in c4b2c7e

	func jetVarMap(binding interface{}) jet.VarMap {
	var bind jet.VarMap
	if binding == nil {
	return bind
	}

But if a layout is specified, it is then used to set a function and panics:

template/jet/jet.go

Lines 219 to 229 in c4b2c7e

	bind := jetVarMap(binding)
	if len(layout) > 0 {
	lay, err := e.Templates.GetTemplate(layout[0])
	if err != nil {
	return err
	}
	bind.Set(e.layout, func() {
	_ = tmpl.Execute(out, bind, nil)
	})
	return lay.Execute(out, bind, nil)
	}

This could be solved either by replacing var bind jet.VarMap with bind := make(jet.VarMap) or by checking if bind is nil (and makeing it if not) in Render right after if len(layout) > 0 {.

// var bind jet.VarMap
bind := make(jet.VarMap)

Or in Render

bind := jetVarMap(binding) 
 if len(layout) > 0 { 
        if bind == nil {
                bind = make(jet.VarMap)
        }
 	lay, err := e.Templates.GetTemplate(layout[0]) 
 	if err != nil { 
 		return err 
 	} 
 	bind.Set(e.layout, func() { 
 		_ = tmpl.Execute(out, bind, nil) 
 	}) 
 	return lay.Execute(out, bind, nil) 
 } 

I would send a pull request, but I'm not sure if it matters to you which way it is fixed. I would think it would be much clearer to put it in jetVarMap and get rid of the other calls to make there, but I guess there was a reason to not do that in the first place.

---

The work around is for the caller of Render to just specify an empty jet.VarMap or fiber.Map but that is not obvious and panicing from forgetting is not great.