Restore Node 24 (and before) behavior as fs.existsSync() now throws deprecation warning

[kroh]

The problem

Execution of lando results in the following error:

$ lando setup
[DEP0187] DeprecationWarning: Passing invalid argument types to fs.existsSync is deprecated
  (Use `node --trace-deprecation ...` to show where the warning was created)

What was wrong

Node 24 introduced deprecation DEP0187: fs.existsSync() now warns when passed anything that isn't a string/Buffer/URL. Older Node silently returned false. Lando relies on that old behavior in many places — it calls fs.existsSync(x) where x is often undefined or an object (e.g. plugin dirs that don't exist, config source objects). Each command bootstraps different subsystems, so different call sites fired.

The fix

Rather than guard dozens of individual call sites (fragile and incomplete), I added a single global shim at Lando's entry point at @lando/core/bin/lando:

const _existsSync = fs.existsSync;
fs.existsSync = function(p) {
  if (typeof p !== 'string' && !Buffer.isBuffer(p) && !(p instanceof URL)) return false;
  return _existsSync.apply(this, arguments);
};

This restores the pre-Node-24 semantics (non-path argument returns false), so behavior is unchanged, just no warning.

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[AaronFeledy]

Thanks for tracking this down! The Node 24 diagnosis looks right, and it should be possible to fix while retaining Node 20 compatibility. Could we avoid globally monkey-patching Node's fs module, though? That changes existsSync() for every dependency in the process and only applies when core is loaded through bin/lando.

I'd suggest a small explicit helper that returns false for non-path values, then use it at the permissive call sites. A regression test covering invalid values on Node 24 would also be helpful. That preserves the old behavior on Node 20 without changing the global API.