Parsing issue for interpolated string

[jeparlefrancais]

I also noticed that the string { {} } does not parse in full-moon in the latest version:

unexpected double brace for interpolated string. try \\{ if you meant to escape

But for better or worse it is supported.

Other test cases:

local _ = `{{ }}` -- err
local _ = `{{hello}}` -- err
local _ = `{ {}}` -- ok
local _ = `{--[[]]{}}` -- ok
local _ = `\{{true}` -- ok
local _ = `{ {true}}` -- ok
local _ = `{ {hello}}` -- err? I don't think I understand why this one errors but not the previous one though
local _ = `\{{hello}}` -- ok

[JohnnyMorganz]

I've reported the inconsistent behaviour of the weird interpolation error upstream: luau-lang/luau#1019