fix(js): handle empty npm view output in release-publish executor - #36397

Current Behavior

nx release publish (the @nx/js release-publish executor) runs npm view <pkg> versions dist-tags --json to check for existing dist-tags before publishing. Some registries — notably GitHub Packages — return empty stdout with a zero exit code when the package exists but has no published versions/dist-tags yet.

In that case JSON.parse('') throws SyntaxError: Unexpected end of JSON input. Because the resulting SyntaxError carries no stdout/stderr, it falls through the E404/404 guards in the surrounding catch block and is surfaced as:

Something unexpected went wrong when checking for existing dist-tags.
 SyntaxError: Unexpected end of JSON input
    at JSON.parse (<anonymous>)
    at runExecutor (.../@nx/js/src/executors/release-publish/release-publish.impl.js)

The publish then aborts, making it impossible to (re)publish a package that exists but has no latest tag yet (e.g. a pre-release that only has a next dist-tag).

Expected Behavior

Empty npm view output is treated the same as the package not existing yet: the dist-tag lookup is skipped and publishing continues, so pre-release / first-time publishes to registries that return empty output succeed.

The JSON.parse is guarded with an empty-output check (result.toString().trim() → fall back to {}). A regression test mocks npm view returning empty stdout and asserts the executor proceeds to publish (three execSync calls: npm --version, npm view, publish) instead of reporting the spurious "Something unexpected went wrong when checking for existing dist-tags" failure.

Related Issue(s)

Fixes #36358