Help identifying Linux-only Foundation-related error in third-party library

Hey, this post is gonna be a bit of a dump and I'm not sure if this is the right category, but here goes.

I'm relatively new to Swift, and I'm developing a library that I'd like to make cross-platform (Darwin and Linux compatible). I'm using the SwiftyJSON library as a dependency, but as it turns out, there's a bug with the library that prevents it from building under Linux. It seems that under Linux, there's an error where defining a custom func < (lhs: NSNumber, rhs: NSNumber), where attempting to use the operator results in an "ambiguous use of operator" between the project's custom definition and Foundation's implementation.

I'm really not sure if I'm explaining this correctly or not, but here's a link to a Github issue that describes the error and here's a PR that attempts to fix the issue with some additional conversation. My question is, is this sort of issue an indicator of a bug in the Linux Foundation implementation, or is this a case that the library devs should be expected to handle? Again, I'd like to use this library in my own cross-platform project, which is how I got here.

Any help would be appreciated!