chore: Standardise Error Codes (#286)

* fix: Misc error handling fixes

* fix: Sandbox error translation

cmd/sandbox/helpers.go

@@ -9,10 +9,10 @@ import (
 	"regexp"
 	"strings"
 
-	"github.com/safedep/pmg/internal/ui"
-	pmgsandbox "github.com/safedep/pmg/sandbox"
 	"github.com/safedep/dry/usefulerror"
 	"github.com/safedep/pmg/errcodes"
+	"github.com/safedep/pmg/internal/ui"
+	pmgsandbox "github.com/safedep/pmg/sandbox"
 	"github.com/spf13/cobra"
 )
 
@@ -70,7 +70,7 @@ func wrapUseful(err error, code, help string) error {
 	if err == nil {
 		return nil
 	}
-	if _, ok := usefulerror.AsUsefulError(err); ok {
+	if hasUsefulError(err) {
 		return err
 	}
 	return usefulerror.NewUsefulError().
@@ -84,7 +84,7 @@ func profileLoadError(err error) error {
 	if err == nil {
 		return nil
 	}
-	if _, ok := usefulerror.AsUsefulError(err); ok {
+	if hasUsefulError(err) {
 		return err
 	}
 	switch {
@@ -99,6 +99,14 @@ func profileLoadError(err error) error {
 		"Failed to load the sandbox profile. Run with --verbose for the underlying cause.")
 }
 
+func hasUsefulError(err error) bool {
+	// AsUsefulError also runs global converters for plain errors like
+	// fs.ErrPermission. Contextual wrappers must only skip errors that already
+	// carry UsefulError details, otherwise generic converters hide command help.
+	var usefulErr usefulerror.UsefulError
+	return errors.As(err, &usefulErr)
+}
+
 func registryInitError(err error) error {
 	return wrapUseful(err, ioErrorCode(err, errcodes.Unknown),
 		"Failed to initialise the sandbox profile registry. Run with --verbose for details.")