Orders GetServiceStatus

[Desmodue]

When calling GetServiceStatus for the Orders API I get "Cannot read property 'list' of undefined" errors.
Looking through the code it would appear that /lib/request.js is checking for param.list when there isn't a param object.

I implemented a quick fix to check if param exists before trying to check if it has properties and executing this block of code. "if (param){" . This fixes the immediate error but I haven't had time to check if this is quite the right place to do this. Maybe the /lib/sections should define an empty params on GetServiceStatus ?

Here is the complete change, line 152 in /lib/request.js

            // Lists need to be sequentially numbered and we take care of that here
            if (param) {
                if (param.list) {
                    const values = _.map(toCollection(value), getValue);

                    _.forEach(values, (value, i) => {
                        this.values[`${param.name}.${i + 1}`] = value;
                    });
                } else {
                    this.values[param.name] = getValue(value);
                }
            }

Quite happy to do a pull request if this is ok

[sjuxax]

I've encountered this when needlessly specifying the MarketplaceId; that is, when I send in a parameter that is not actually specced out by MWS. I added a similar hack to bypass this error, while also adding this to the log:

if (param === undefined) {
    console.log(`Couldn't find ${paramName} in request spec. Maybe you don't need it?`)
}

MWS seems to do fine with the extraneous variable so we don't stop the request, but just notify the user they may not need to send it in.