Key holding the authenticated principal, or null on an anonymous request.
The null default means context.get(userContext) resolves to null rather
than throwing when no principal is attached — React Router's get() throws
No value found for context for an unset key that has no default.
Key holding the authenticated principal, or
nullon an anonymous request.The
nulldefault meanscontext.get(userContext)resolves tonullrather than throwing when no principal is attached — React Router'sget()throwsNo value found for contextfor an unset key that has no default.