Variable Uninitialized Error While Building

[dakanji]

I'm following the instructions on building on MacOS and came across an error. I'm pretty sure this is user error, not a bug, so I'm posting here rather than issues (please let me know if this is improper, I'm not familiar with the proper etiquette).

I've made it to "Build Required BaseTools C Tool Binaries" and when running
make -C BaseTools/Source/C
I get this error
error: variable 'StringIndex2' is uninitialized when used here [-Werror,-Wuninitialized]

I've poked around a bit online and found posts about a similar issue but I'm not quite sure how to implement it to this build. The full output is in the attached screenshot, there's a couple things that line up that I wouldn't be able to get proper here.

Originally posted by @bcskillings in https://github.com/dakanji/RefindPlus/discussions/43