Text function and emojis causes jsaddle errors in certain cases

[alexfmpe]

Porting from obsidiansystems/obelisk#1055.
Happens with

• jsaddle-warp-0.9.8.2 / ghc 8.10
• jsaddle-warp-0.9.9.0 / ghc 9.6

Works:
text "👋 Contact Support"

and

text "👋"

Causes JSaddle Error:

text "👋" >> text "Contact Support"

JSaddle Error:

jsaddle Results decode failed : "{"tag":"BatchResults","contents":[215,{"tag":"Success","contents":[[],[{"tag":"ValueToStringResult","contents":"\udc4bContact Support"}]]}]}"
CallStack (from HasCallStack):
error, called at src/Language/Javascript/JSaddle/WebSockets.hs:103:50 in jsaddle-warp-0.9.8.2-DFAPM2CvatBGFm3L9xaA1B:Language.Javascript.JSaddle.WebSockets

[hsyl20]

👋 is encoded as:

• UTF-32: 0001f44b
• UTF-16: d83d dc4b
• UTF-8: f0 9f 91 8b

So here it looks like we encode it to UTF-16 and then drop the first code unit (d83d). So in the end result instead of having "\u1f44bContact Support" we get "\udc4bContact Support".

Could you dump rule's rewrites with GHC's -ddump-rule-rewrites to see if a fusion rule in Data.JSString.Internal.Fusion fire?