make: "varmod-range.mk" line 53: Invalid number: x}Rest" != "Rest"

make: "varmod-range.mk" line 53: Malformed conditional ("${:U:range=x}Rest" != "Rest")
make: Unknown modifier 'x'
make: "varmod-range.mk" line 62: Malformed conditional ("${:U:range=0x0}Rest" != "Rest")
make: Unknown modifier 'r'
make: "varmod-range.mk" line 78: Malformed conditional ("${a b c:L:rang}Rest" != "Rest")
make: Unknown modifier 'r'
make: "varmod-range.mk" line 85: Malformed conditional ("${a b c:L:rango}Rest" != "Rest")
make: Unknown modifier 'r'
make: "varmod-range.mk" line 92: Malformed conditional ("${a b c:L:ranger}Rest" != "Rest")
make: Fatal errors encountered -- cannot continue
make: stopped in unit-tests
exit status 1