[BUG] Exception if there's a root path in spec

Just tried to integrate this library into my project and I just found a case where the library fails.

There is an issue with the getPathToMethodName function.

When I have a root path (/) in the paths object of the spec, the library crashes: “Cannot read property ‘toUpperCase’ of undefined”.

It’s caused by line 116, but originates from line above.

If the result variable is an empty string it throws.

I “fixed” it by doing this before calling the getTypescriptCode function:

if (spec.paths.hasOwnProperty('/')) {
    let prop = spec.paths['/'];
    delete spec.paths['/'];
    spec.paths['/index'] = prop;
}

This solution fixes the issue partially, because now the target path in the generated code is wrong.

The solution to the issue might be using an alias for the / path, like index for example.

[mtennoe]

Merged and published as 3.0.3. Thanks @sjwilczynski! Please reopen if it doesnt solve the problem for you @VentyCZ

[sjwilczynski]

Created a PR for that.