The error action is controlled by error handlers established within
the executing code and by the current default error handler set by
options(error=)
. The error is first signaled as if using
signalCondition()
. If there are no handlers or if all handlers
return, then the error message is printed (if
options("show.error.messages")
is true) and the default error
handler is used. The default behaviour (the NULL
error-handler) in interactive use is to return to the top level
prompt or the top level browser, and in non-interactive use to
(effectively) call q("no", status = 1, runLast = FALSE
).
The default handler stores the error message in a buffer; it can be
retrieved by geterrmessage()
. It also stores a trace of
the call stack that can be retrieved by traceback()
.
Errors will be truncated to getOption("warning.length")
characters, default 1000.
If a condition object is supplied it should be the only argument, and
further arguments will be ignored, with a warning.