fail function
Prints message
to stderr and exits the current script.
Within a Script.capture block, this throws a ScriptException that causes
the script to exit with the given exitCode
. Elsewhere, it exits the Dart
process entirely.
Implementation
Never fail(String message, {int exitCode = 1}) {
currentStderr.writeln(message);
var scriptName = Zone.current[scriptNameKey];
if (scriptName is String) {
throw ScriptException(scriptName, exitCode);
} else {
exit(exitCode);
}
}