Organize backend into product executable and shared Go modules

backend/shared/errors/reason.go

@@ -0,0 +1,19 @@
+package merrors
+
+import (
+	"errors"
+	"strings"
+)
+
+func Reason(err error) (string, bool) {
+	var reasoned interface {
+		Reason() string
+	}
+	if errors.As(err, &reasoned) {
+		reason := strings.TrimSpace(reasoned.Reason())
+		if reason != "" {
+			return reason, true
+		}
+	}
+	return "", false
+}