rlang 0.4.2

• New cnd_header(), cnd_body() and cnd_footer() generics. These
  are automatically called by conditionMessage.rlang_error(), the
  default method for all rlang errors.

  Concretely, this is a way of breaking up lazy generation of error
  messages with conditionMessage() into three independent
  parts. This provides a lot of flexibility for hierarchies of error
  classes, for instance you could inherit the body of an error message
  from a parent class while overriding the header and footer.

• The reminder to call last_error() is now less confusing thanks to
  a suggestion by @markhwhiteii.

• The functions prefixed in scoped_ have been renamed to use the
  more conventional local_ prefix. For instance, scoped_bindings()
  is now local_bindings(). The scoped_ functions will be
  deprecated in the next significant version of rlang (0.5.0).

• The .subclass argument of abort(), warn() and inform() has
  been renamed to class. This is for consistency with our
  conventions for class constructors documented in
  https://adv-r.hadley.nz/s3.html#s3-subclassing.

• inform() now prints messages to the standard output by default in
  interactive sessions. This makes them appear more like normal output
  in IDEs such as RStudio. In non-interactive sessions, messages are
  still printed to standard error to make it easy to redirect messages
  when running R scripts (#852).

• Fixed an error in trace_back() when the call stack contains a
  quosured symbol.

• Backtrace is now displayed in full when an error occurs in
  non-interactive sessions. Previously the backtraces of parent errors
  were left out.