### Please describe the problem.

Building the latest version from source, whatever method I use eventually fails on the language-javascript-0.7.1.0 dependency. The error (stack output) below.



### What steps will reproduce the problem?

1. Install ghc 8.10.7 via ghcup
2. Check out latest source
3. Issue any of the supported build commands, watch the failure eventually happen

### What version of git-annex are you using? On what operating system?

git master (tag 8.20211123 has the same issue)

### Please provide any additional information below.

[[!format sh """
# If you can, paste a complete transcript of the problem occurring here.
# If the problem is with the git-annex assistant, paste in .git/annex/daemon.log

language-javascript              > Configuring language-javascript-0.7.1.0...
language-javascript              > build
language-javascript              > Preprocessing library for language-javascript-0.7.1.0..
language-javascript              > happy: src/Language/JavaScript/Parser/Grammar7.y: hGetContents: invalid argument (invalid byte sequence)

# End of transcript or log.
"""]]

### Have you had any luck using git-annex before? (Sometimes we get tired of reading bug reports all day and a lil' positive end note does wonders)

Yes, it's wonderful.

> Upstream bug is <https://github.com/simonmar/happy/issues/157>  
> and this cannot be fixed in git-annex, so [[done]] --[[Joey]]
