Issue with make and Mac homebrew

Question

I'm trying to use Homebrew on macOS and whenever it comes time to use make, it shows this error

Last 15 lines from /Users/milesacq/Library/Logs/Homebrew/webp/02.make:
make[2]: *** Waiting for unfinished jobs....
make[2]: *** [libwebpdecode_la-io_dec.lo] Error 1
make[2]: *** [libwebpdecode_la-alpha_dec.lo] Error 1
1 error generated.
1 error generated.
make[2]: *** [libwebpdecode_la-vp8_dec.lo] Error 1
1 error generated.
make[2]: *** [libwebpdecode_la-buffer_dec.lo] Error 1
1 error generated.
make[2]: *** [libwebpdecode_la-quant_dec.lo] Error 1
1 error generated.
make[2]: *** [libwebpdecode_la-idec_dec.lo] Error 1
make[2]: *** [libwebpdecode_la-tree_dec.lo] Error 1
make[1]: *** [install-recursive] Error 1
make: *** [install-recursive] Error 1

I've tried "brew clean", "brew update", "brew upgrade", deleting and reinstalling make and the rest of the developer tools, and even deleting the Homebrew/webp folder in case something was wrong with the makefile itself

Any insights would be appreciated

EDIT: This seems to be caused by missing header files cstddef.h, string.h and SDL.h, how do I fix this? I have the latest version of the developer tools and I've tried uninstalling and reinstalling