fix user status done undefined

[csvwolf]

My Leetcode Status is :

Easy 39/97 (40.21%) [..............................]
Medium 4/198 (2.02%) [..............................]
Hard 0/83 (0.00%) [..............................]

But when I run, it will throw an error since I have not done hard problems yet:

                    throw new TypeError(sprintf("[sprintf] expecting number but found %s", get_type(arg)))
                    ^

TypeError: [sprintf] expecting number but found undefined

So I use a default value to fix it. Hope it's useful for the project.

[skygragon]

Thanks for patching!

The default value is clean and easy while it's a new feature from es6/es2015, which means older nodejs distributions don't support it by default. For example, in nodejs v5.6.0, we must use "--harmony_default_parameters" in calling to make it working.

IMHO It would be better to use a common way to fit different nodejs versions, e.g.

prettyLine('Easy', stats.acEasy || 0, stats.allEasy);

[csvwolf]

@skygragon Due to the compatibility, I suggest to modify the code in the function to avoid process every sentence of prettyLine

[skygragon]

LGTM. Thanks!