error message contains invalid type reference

loading
```
version=2

rule=:a %
        {"type":"alternative",
         "parser": [
                    {"name":"num", "type":"string", "matching.mode":"lazy"} 
                   ]
        }% b
```

will give out
```
liblognorm error: rulebase file boo.rb[8]: invalid param for hexnumber: "lazy"
```

version 2.0.4

while type hexnumber not used in the rule