Fails ES5 compatibility check

[nikhilSriva]

I am using the Pako library in my project, and as part of my CI pipeline, I validate that all bundled JavaScript files are compatible with ES5 syntax. This is done using the acorn parser with the following command:

find ./js/assets/ -name "*.js" -type f -exec acorn --ecma5 --silent {} + ;

While other libraries like zlib work fine, integrating Pako causes the pipeline to fail with the following error:
The keyword 'let' is reserved (./js/assets/example.js:1:10)

What can be a possible fix here?

Thanks in advance!