Examine impact of R 4.0 changes

[aryoda]

R 4.0.0 has been released today and brings some changes and features that might impact tryCatchLog.

Examine the impact of the changes...

• The internal traceback object produced when an error is signalled
  (.Traceback), now contains the calls rather than the deparse()d
  calls, deferring the deparsing to the user-level functions
  .traceback() and traceback(). This fulfils the wish of PR#17580,
  reported including two patch proposals by Brodie Gaslam.

• assertError() and assertWarning() (in package tools) can now
  check for specific error or warning classes via the new
  optional second argument classes (which is not back compatible
  with previous use of an unnamed second argument).

• stopifnot() now allows customizing error messages via argument
  names, thanks to a patch proposal by Neal Fultz in PR#17688.

• stopifnot() gets new argument exprObject to allow an R object of
  class expression (or other 'language') to work more consistently,
  thanks to suggestions by Suharto Anggono.

• New globalCallingHandlers() function to establish global
  condition handlers. This allows registering default handlers for
  specific condition classes. Developed in collaboration with
  Lionel Henry.

• New function tryInvokeRestart() to invoke a specified restart if
  one is available and return without signaling an error if no such
  restart is found. Contributed by Lionel Henry in PR#17598.

• New classes argument for suppressWarnings() and
  suppressMessages() to selectively suppress only warnings or
  messages that inherit from particular classes. Based on patch
  from Lionel Henry submitted with PR#17619.

• R_withCallingErrorHandler is now available for establishing a
  calling handler in C code for conditions inheriting from class error.

[aryoda]

Some unit tests for globalCallingHandlers together with tryCatchLog would be nice...

But I suggest to reject and close this issue (nobody complained so far about R 4.0 with tryCatchLog).