Compiling Emacs in mingw ucrt runtime

[Arthur Miller]

I think I have found it!

make[3]: Leaving directory '/c/Users/arthu/repos/emsrc/ucrt-02-21/lisp'
make -C ../admin/unidata all EMACS="../../src/bootstrap-emacs.exe"
make[3]: Entering directory 
'/c/Users/arthu/repos/emsrc/ucrt-02-21/admin/unidata'
"../../src/bootstrap-emacs.exe" -batch --no-site-file --no-site-lisp -f 
batch-byte-compile uvs.el
C:\Users\arthu\repos\emsrc\ucrt-02-21\src\bootstrap-emacs.exe: Write error to 
standard output: No such file or directory
make[3]: *** [Makefile:61: uvs.elc] Error 1

I can open uvs.el; if it is that file it is about; I have no idea what it does;
it seems to be dumping something; but from the comment, can it possibly be some
problem with encoding?

If that file is the problem ....