Guard module-scope moveBefore feature-detect for DOM-less import

[codetalcott]

Problem

Importing morphlex in a DOM-less environment (bare Node / SSR) throws on import, before any morph function is called:

ReferenceError: Element is not defined

The cause is the module-scope feature-detect at the top of src/morphlex.ts:

const SUPPORTS_MOVE_BEFORE = "moveBefore" in Element.prototype

Element is dereferenced at module-evaluation time, so any environment without a DOM global (Node without a DOM shim, SSR/prerender, a bundler evaluating the module in Node) crashes on import. This is the only module-scope DOM access in the file — every other Element/Node/document reference is inside a function body or a type, so guarding this one line makes the whole module importable without a DOM.

Fix

const SUPPORTS_MOVE_BEFORE = typeof Element !== "undefined" && "moveBefore" in Element.prototype

• In a browser: typeof Element === "function", so "moveBefore" in Element.prototype is evaluated exactly as before — behavior is identical.
• Without a DOM: short-circuits to false, so moveBefore() falls back to insertBefore (moot in practice, since morphing needs a real DOM to run — this only makes the import safe).

This does not attempt to make morphing work headless; it only prevents the import-time crash so morphlex can be pulled into modules that are also evaluated in Node (the common SSR / bundler case).

Test

Added test/new/ssr-import.test.ts — stubs Element to undefined, resets the module registry, and asserts the module imports and still exposes morph / morphInner. It fails on main (ReferenceError: Element is not defined) and passes with this change, so it guards the regression. It also covers the new typeof Element !== "undefined" branch, which the happy-dom test env (where Element is always defined) otherwise wouldn't exercise.

Validation

# Fails before this change, passes after:
npx vitest run test/new/ssr-import.test.ts

# Existing node suite unchanged (DOM behavior identical):
#   test/morphlex*.test.ts — 148 passed

# End-to-end, against a built bundle with no DOM present:
node --input-type=module -e "await import('./dist/morphlex.min.js').then(m => console.log(typeof m.morph))"
#   before: ReferenceError: Element is not defined
#   after:  function

prettier --check clean on both files; tabs/no-semicolon style matches the surrounding code.

Context

Found while making a downstream library (which vendors morphlex for DOM morphing) importable in bare Node — we currently work around it with a guarded globalThis.Element shim ahead of the morphlex import. This one-liner removes the need for that shim for anyone importing morphlex in a mixed Node/browser codebase.