Installation fails on macOS

[epipping]

Here's what I'm seeing:

% npm install spellchecker

> spellchecker@3.4.1 install /Users/pipping/node_modules/spellchecker
> node-gyp rebuild

[...]

  CXX(target) Release/obj.target/spellchecker/src/spellchecker_mac.o
../src/spellchecker_mac.mm:141:13: error: cannot initialize a variable of type 'NSString *' with an rvalue of type
      'const NSString *'
  NSString* globalLang = currentGlobalLanguage ? currentGlobalLanguage : autoLangauge;
            ^            ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../src/spellchecker_mac.mm:142:13: error: cannot initialize a variable of type 'NSString *' with an rvalue of type
      'const NSString *'
  NSString* ourLang = this->spellCheckerLanguage ? this->spellCheckerLanguage : autoLangauge;
            ^         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
2 errors generated.

This is on the beta of macOS 10.13 but I have no way of checking if the issue is 10.13-specific.