Non-compilable Javascript files

Hello, I was trying to compile some Javascript files. Many of them don't compile because of this issue. Is it a bug from javy itself? The files look like they have no errors, only warnings.
Other pretty common errors that show up when compiling with javy are as follows: "expected token: '(' " or "unexpected token in expression: '}' " .
Thank you

osboxes@osboxes:~/Desktop$ RUST_BACKTRACE=1 ./javy build Js_fix/20151215_6cdcaffda926f503edc872256d65dea7.js

thread '' panicked at crates/plugin-api/src/lib.rs:119:10:
called `Result::unwrap()` on an `Err` value: Error:[function.mjs]:7:24 invalid redefinition of global identifier in module code
at function.mjs:7:24

note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
Error: JS compilation failed

Stack backtrace:
0: anyhow::error::::msg
1: javy_codegen::plugin::Plugin::compile_source
2: javy_codegen::Generator::generate
3: javy::main
4: std::sys::backtrace::__rust_begin_short_backtrace
5: main
6: __libc_start_call_main
at ./csu/../sysdeps/nptl/libc_start_call_main.h:58:16
7: __libc_start_main_impl
at ./csu/../csu/libc-start.c:392:3
8: _start