Use optionalValue for error reporter initialization as well

lib/node-application.nix

@@ -5,6 +5,7 @@
 		let
 			buildNode2nixPackage = (import ./build/node2nix-package.nix) args;
 			errorReporter = (import ./node-error-reporter) args;
+			optionalValue = (import ./util/optional-value.nix);
 		in let
 			serviceName = "node-${name}";
 			cfg = config.services."${serviceName}";
@@ -14,11 +15,11 @@
 				inherit src setupCommands;
 			};
 
-			errorReporterModule = if hasErrorReporting then (errorReporter {
+			errorReporterModule = optionalValue hasErrorReporting (errorReporter {
 				application = application;
 				applicationName = name;
 				errorPath = errorPath;
-			}) else null;
+			});
 		in {
 			imports = [
 				errorReporterModule