`unstable-string-to-number`

The `string->number`

procedure is supposed to parse
numbers out of strings and return them, or return `#f`

if the
string is not a syntactically valid number. That leaves to interpretation
the corner case where the argument string contains a syntactically
legitimate expression for a number that nonetheless is not a number, namely
the likes of `1/0`

. Should `string->number`

return
`#f`

or fall through to the number construction (which will
presumably signal a division by zero)?