The message is misleading. "result" is the one at line 325 in system.nim, i.e. the HSlice which is returned by the proc.
When instanciating the slice (".."), the fields "a" and "b" of "result" (a
slice) should be initialized with 0. But "b" is of type "range[8..10] and
cannot be initialized with this value. So, the compiler emits a warning.
To avoid this warning, you simply can write "assert c in DIGITS[0 ..<
radix.int]".
