fix(*): patch expanduser to be more friendly to OpenResty environment

[windmgc]

Summary

pl.path.expanduser may return with nil, err when received a path argument starting with ~ but $HOME(or other home path related) environment variable is not present. This PR adds proper error handling code when calling expanduser.

[github-actions]

Luacheck Report

76 tests    0 ✅  0s ⏱️
 1 suites   0 💤
 1 files    76 ❌

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Results for commit d0f91c0.

♻️ This comment has been updated with latest results.

[Tieske]

Then userfriendly way to resolve this is to read the env vars in the config module along with the others (the AWS specific ones).

Probably best to copy the Penlight code here, and modify it to fall back to the cached variables.

Just ensure we also cater for Windows (despite we're not using it)

[windmgc]

A bug has also been detected that expanded file path is not being used to read content, see:

lua-resty-aws/src/resty/aws/config.lua

Line 185 in 1f3b8bb

local contents, err = pl_config.read(filename, { variabilize = false })

I fixed it in the latest commit

[windmgc]

@Tieske Yes, I intended to not handle the error returned by these three functions as the expanduser error seems to be not fatal for these three functions(if it fails the function will return something else or follow other logic), but it is a fatal error for load_file, so I only handled the error in load_file.

In the last commit, I added some debug logs to these three functions in case we encounter error and have problem debugging them. Please review again! Thanks

[Tieske]

BTW; does need a changelog entry!