use of string.sub generates SYN characters

[Todd Wegner <twwegner@...>]

I would like to understand why the following code produces SYN characters (0x16) in Lua53 on Linux.

The SYN occur whenever split divides a multi-byte character in half.

Why does string.sub return SYN rather than respective bytes.

Code:

local space = string.byte(' ')
local text = utf8.char(0x92e,0x947,0x930,0x93e, space, 0x928, 0x93e, 0x92e, space, 0x932,0x942,0x905, space, 0x939,0x948, 0x964)

local split = 1
local lh = string.sub(text, 1, split)
local rh = string.sub(text, split+1)

print('text', text)
print('lh', lh)
print('rh', rh)

Output:

text    मेरा नाम लूअ है।
lh    मSYN SYN
rh    SYN रा नाम लूअ है।

Thanks