Better error if no destionationXCoordinate or destinationYCoordinate

[gavinr]

If you don't have a valid X or Y in your data (for example, if one of them is empty/blank), you get a weird error, Uncaught TypeError: Cannot read property 'clone' of null. I know it's up to me as a user of the library to make sure I have good data, BUT in the case I don't for whatever reason, would be nice to have a more instructive error message.

I think this can be done by wrapping these lines in a classic .hasOwnProperty(). This might be a bit verbose though ... what do you think?

[jwasilgeo]

Thanks, @gavinr, I think that's a good error handling enhancement. Maybe wrap it up in a try/catch, too? Regardless, I could see it providing the error somehow in the console to try to inform which incoming feature row is not quite right, but still let the forEach loop continue with any other valid features. PRs welcome! 😉