fix ERL_ROOTDIR issues

[jhheider]

see #56 (comment)

[Copilot]

Pull request overview

This PR fixes ERL_ROOTDIR environment variable handling issues by adding support for bash-style default value syntax (${FOO:-bar}) in the GitHub Actions environment variable parser. The changes ensure that environment variables can specify fallback values, which is particularly important for Erlang's ERL_ROOTDIR configuration.

• Adds regex pattern to handle ${FOO:-bar} syntax (use default if variable is unset or falsy)
• Excludes no-import-prefix and no-unversioned-import lint rules for Deno imports

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
action.js	Adds support for bash-style default value syntax (${FOO:-bar}) in environment variable substitution
deno.json	Excludes two Deno-specific lint rules to accommodate existing import patterns

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[Copilot]

The use of || operator here may not correctly handle environment variables that are set to an empty string. In bash, ${FOO:-bar} uses the default value when FOO is unset or empty, but process.env[key] || defaultVal will use the default value for any falsy value including 0 or false.

Consider using ?? defaultVal instead to match bash behavior more closely, or explicitly check for undefined/null:

(_, key, defaultVal) => (process.env[key] ?? defaultVal)

However, note that even ?? won't treat empty strings the same as bash does. For exact bash parity, you'd need:

(_, key, defaultVal) => (process.env[key] === undefined || process.env[key] === '') ? defaultVal : process.env[key]

Suggested change

	(_, key, defaultVal) => process.env[key] || defaultVal,
	(_, key, defaultVal) => (process.env[key] === undefined || process.env[key] === '') ? defaultVal : process.env[key],

[Copilot]

The comment states ${FOO:-bar} > $FOO || "bar" but this is misleading. In bash, ${FOO:-bar} means "use $FOO if set and non-empty, otherwise use bar". The implementation uses the JavaScript || operator which has different semantics—it will also use the default for falsy values like 0, false, or empty string (though empty string matches bash behavior).

Consider updating the comment to be more accurate:

// handles ${FOO:-bar} - uses default if FOO is unset or falsy

Or if you want to strictly match bash behavior (use default only when unset or empty):

// handles ${FOO:-bar} - uses default if FOO is unset or empty (bash-style)

Suggested change

	// handles ${FOO:-bar} > $FOO || "bar"
	// handles ${FOO:-bar} - uses default if FOO is unset or falsy