Hello,
I run following code in ch 1.11.19(debug)，and it will crash by an assertion.

let b = [1.1, 2.2, 3.3];
b[4294967294] = 3;
Array.prototype.copyWithin.call(b, 0, 1);

Crash output:

ASSERTION 7690: (/.../ChakraCore-1.11.19/lib/Runtime/Library/JavascriptArray.cpp, line 9309) direction == -1 || (fromVal + count < MaxArrayLength && toVal + count < MaxArrayLength)
 Failure: (d

See: https://www.boost.org/doc/libs/1_58_0/doc/html/program_options/tutorial.html#idp337609360

If we want to be more idiomatic C++ and use less C-style stuff and enable more complex command-line options, would this be a good improvement?

There are common 'program stubs' which are used as the entry-point for many commands:

• https://github.com/HarryR/ethsnarks/blob/master/src/stubs.cpp

Currently the kv store is unqlite. It will be good to integrate LevelDb with Bun