Different behavior to provide information to the user (either a message, a warning or an error).
msg_warn_error(msg, type, startup = FALSE)character string, text message.
character string, among "msg" to print a message, "warn" for
to raise a warning, and "error" to raise an error.
boolean indicating if the function is called at startup or not.
Ghislain Durif
If type = "msg", then a message with content msg is printed. If
type = "warning", then a warning with message msg is raised. And if
type = "error", then an error with message msg is raised.
If type = "msg" and startup = TRUE, then packageStartupMessage()
function is used instead of message().