fallback for `find-cache-dir`

[alexander-akait]

• Operating System: no matter
• Node Version: no matter
• NPM Version: no matter
• webpack Version: no matter
• terser-webpack-plugin Version: latest

Expected Behavior

find-cache-dir can return null so we need fallback for this using os.tmpdir()

Actual Behavior

No fallback

Code

No need

How Do We Reproduce?

It is hard, but in theory can happens