better op names + fixing issue with op chaining in errors

internal/app/api/pkg/handler/html.go

@@ -4,21 +4,26 @@ import (
 	"github.com/labstack/echo/v4"
 	"github.com/thecodingmachine/gotenberg/internal/app/api/pkg/context"
 	"github.com/thecodingmachine/gotenberg/internal/pkg/printer"
+	"github.com/thecodingmachine/gotenberg/internal/pkg/standarderror"
 )
 
 // HTML is the endpoint for converting
 // HTML to PDF.
 func HTML(c echo.Context) error {
+	const op = "handler.HTML"
 	ctx := context.MustCastFromEchoContext(c)
 	r := ctx.Resource()
 	opts, err := r.ChromePrinterOptions()
 	if err != nil {
-		return err
+		return &standarderror.Error{Op: op, Err: err}
 	}
 	fpath, err := r.Fpath("index.html")
 	if err != nil {
-		return err
+		return &standarderror.Error{Op: op, Err: err}
 	}
 	p := printer.NewHTML(fpath, opts)
-	return convert(ctx, p)
+	if err := convert(ctx, p); err != nil {
+		return &standarderror.Error{Op: op, Err: err}
+	}
+	return nil
 }