[!WARNING] This package contains internal utilities shared across the Lexical packages: invariant/devInvariant, createError, dev/prod error- and warning-message formatting, warnOnlyOnce, and the LEXICAL_VERSION constant. These are bound to the build's transforms and are inlined into every other package rather than shipped as a runtime dependency, so it is published only so the modules resolve through normal package resolution — including the source export condition used when developing against a linked checkout.

It is not a public API. Import from lexical and the @lexical/* feature packages instead. Nothing here follows semver and any export may change or disappear without notice.

createError('Message with %s', value) constructs an Error without throwing it, for example to pass to an editor's onWarn handler. It shares invariant's literal-message and %s argument convention, including production error-code extraction, and can be used inside expressions.

The transform recognizes the default import from @lexical/internal/createError (or its .js alias), including renamed imports. Unrelated or shadowed functions with the same name are left alone. Generated calls use separate createDevError and createProdError runtime helpers so bundled output can pass through the transform again.

Warnings routed through createError, including the update-cascade warning, use the minified error message in production builds with extracted error codes. Arguments such as the editor namespace are encoded as v parameters in the decoder URL instead of appearing directly in the message text. Telemetry that matches the full development warning text must account for that production form.