v5.6.0

A name the language has is not a program's to declare.

Changes

• A name the language already has is E118, where it is declared. A
  page's state env compiled every read to the build's settings and every
  write to the state: "{env}" showed [object Object], env == "prod"
  was never true, and wf check said nothing. A loop's t hid the
  translation function inside the loop the same way. Such a name is now
  refused as a state, derived, persist or let, a prop, a route or
  action parameter, a loop item, a lambda's parameter, a binding of if let, match or a slot, and as a top-level const, data, image,
  store or api. The names are env, params, locale and dir; the
  values the browser keeps current (now, viewport, query, hash,
  theme, network, update); the language's functions (t, format,
  ago, log, navigate, fetch, uuid, every, after, …); the
  words a statement is written with (state, action, let, if,
  show, match, style, on, …); and, at the top level, the runtime's
  WF. The message suggests a name of your own where there is a usual one
  — target for env, search for query, scheme for theme.
  event, e, value, key and the browser's globals stay yours, and so
  does any name as a field, a map key or an enum case.
• A top-level const env is refused where it is written. It was
  refused only when the build read its own bundle back, as "a bug in
  WebFluent" (E901).

Upgrading

A program that declares one of these names stops at E118, on the line
that declares it; rename it and its reads. The usual ones are a loop's or a
lambda's t (for t in todos, items.filter(t => …) — todo, item),
state query (search), persist theme (scheme), a route parameter or
state env (target, stage) and an action named update (edit). The
guide, the examples and the site were renamed the same way.

Full Changelog: v5.5.0...v5.6.0