Malformed record modify `{ key | }` creates EXTRA COMMA error

[jfine2358]

Quick Summary: Malformed record modify { key | } creates EXTRA COMMA error.

SSCCE

$ elm repl
---- Elm 0.19.1 ----------------------------------------------------------------
> { key | }
-- EXTRA COMMA ------------------------------------------------------------ REPL
I am partway through parsing a record, but I got stuck here:
3|   { key | }
             ^
Trailing commas are not allowed in records.

There is no comma, let alone an extra comma. The error message could be improved. (I suspect that allowing { key | } would be contrary to Elm practice.)

• Elm: 0.19
• Browser: None
• Operating System: Not relevant (Linux).

Additional Details

I suspect that {key | puts the compiler into a prev_token = Comma state.

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