Syntax error for a valid script

[certik]

The following script:

#! /bin/sh

if test -n "${xml_catalog_files_libxml2:-}"; then
    export XML_CATALOG_FILES="${xml_catalog_files_libxml2}"
else
    unset XML_CATALOG_FILES
fi
unset xml_catalog_files_libxml2

Gives:

$ source "/Users/ondrej/miniforge3/envs/spawn2/etc/conda/deactivate.d/libxml2_deactivate.sh"
Syntax error:   × Failed to parse input
  ╰─▶ Failure to parse at Pos((3, 43))
   ╭────
 1 │ if test -n "${xml_catalog_files_libxml2:-}"; then
   ·                                           ┬
   ·                                           ╰── expected QUOTED_ESCAPE_CHAR, QUOTED_CHAR, VARIABLE_EXPANSION, SUB_COMMAND, or EXIT_STATUS
   ╰────
  help: expected QUOTED_ESCAPE_CHAR, QUOTED_CHAR, VARIABLE_EXPANSION,
        SUB_COMMAND, or EXIT_STATUS

[certik]

The following workaround parses:

#! /bin/sh

if [ -n "${xml_catalog_files_libxml2:-}" ]; then
    export XML_CATALOG_FILES="${xml_catalog_files_libxml2}"
else
    unset XML_CATALOG_FILES
fi
unset xml_catalog_files_libxml2

but panics:

$ RUST_BACKTRACE=1 shell /Users/ondrej/miniforge3/envs/spawn2/etc/conda/deactivate.d/libxml2_deactivate.sh
thread 'main' panicked at crates/deno_task_shell/src/shell/execute.rs:1045:42:
not yet implemented
stack backtrace:
   0: _rust_begin_unwind
   1: core::panicking::panic_fmt
   2: core::panicking::panic
   3: deno_task_shell::shell::execute::execute_command::{{closure}}
   4: deno_task_shell::shell::execute::execute_sequence::{{closure}}
   5: deno_task_shell::shell::execute::execute_sequential_list::{{closure}}
   6: shell::execute::execute::{{closure}}
   7: tokio::runtime::park::CachedParkThread::block_on
   8: shell::main
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.