* Handle input errors for --indent
Handle malformed and overflowing arguments. Also, forbid leading and
trailing spaces to match the behavior of tonumber from commit ce0e788
(improve tonumber/0 performance by parsing input as number literal,
2024-03-02).
* Do not skip leading whitespace in jvp_strtod
`jvp_strtod` skips leading whitespace, but its decnum counterpart
`decNumberFromString` (called within `jv_number_with_literal`) does not.
Those two are called interchangeably, so it leads to inconsistent
behavior depending on whether the decnum feature is enabled.
Additionally, `classify`, used in the token scanner, only considers
[ \t\n\r] to be whitespace, but `jvp_strtod` consumes the larger set
[ \t\n\v\f\r], so those extra characters are considered literals.
Changing this deviates from the behavior of `strdod` from <stdlib.h> and
is technically a breaking API change, since it is a public symbol.
Thalia Archibald