Repl fails to parse some json inputs

[sigmaSd]

Trying this line in the repl

JSON.parse('{"x": "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa🌎"}')

fails with Unterminated string literal

It only fails if there is exactly 99 'a' (or any character) before the world unicode
If I add or remove a couple of characters before the unicode it works.

meta:
deno 1.14.3 (release, x86_64-unknown-linux-gnu)
v8 9.4.146.19
typescript 4.4.2

[andreubotella]

Might be related to #10542

[lucacasonato]

For reference, adding .x to the end of the statement makes it work again. Probably a bug in our object formatting code.

[lucacasonato]

Yeah, this looks like a combination of bugs in our object formatting code, and REPL code. Running this code demonstrates what is going on pretty well:

console.log(JSON.parse(`["98 chars", "${"x".repeat(98)}🌎"]`));
console.log(JSON.parse(`["99 chars", "${"x".repeat(99)}🌎"]`));
console.log(JSON.parse(`["100 chars", "${"x".repeat(100)}🌎"]`));

❯❯❯ deno run test.js
[
  "98 chars",
  "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx🌎"
]
[
  "99 chars",
  "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx�..."
]
[
  "100 chars",
  "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx..."
]

The formatted splits multi byte unicode chars in half. We need to do two things:

a) update formatting code to not chop multi byte characters in half
b) fix REPL so it doesn't error on surrogate pairs (this is actually an issue with our V8 inspector related code)

I'll keep this issue for a), while b) is already tracked in #12226

[sigmaSd]

the issue seems fixed in the latest version, the reproduction code doesn't error anymore