Problem

When using @tanstack/table-core in vanilla JS without a bundler (e.g., via ES module importmaps in Rails), a ReferenceError: process is not defined is thrown because the source code contains raw process.env.NODE_ENV references.

As reported in #6078, the ESM build output preserves these references without any transformation, and environments without Node.js globals (browser ESM via importmaps, Deno, etc.) crash on them.

Root Cause

The source code directly accesses process.env.NODE_ENV for development-only warnings and debug logging. While bundlers like Vite/Webpack replace these at build time, the published ESM output retains them as-is, causing errors in unbundled environments.

Fix

Introduced a isDev() utility function that safely checks for the existence of process before accessing process.env.NODE_ENV:

export function isDev(): boolean {
  return (
    typeof process !== 'undefined' &&
    process.env?.NODE_ENV !== 'production'
  )
}

Replaced all direct process.env.NODE_ENV checks across table-core with calls to isDev().

Files changed:

• packages/table-core/src/utils.ts — Added isDev() utility
• packages/table-core/src/core/column.ts — 2 occurrences
• packages/table-core/src/core/table.ts — 3 occurrences
• packages/table-core/src/utils/getFilteredRowModel.ts — 1 occurrence

Closes #6078