make Optimized server - no input files error

[CSchank]

When trying to make build/bin/RunOptimizedProdServer, I get the following error with IHP v1.4.1:

$ make build/bin/RunOptimizedProdServer 
/nix/store/24c201n06yjp6bcafkd941c83r99rpmw-ihp-env-var-backwards-compat/Makefile.dist:130: warning: undefined variable 'APP_RTS_FLAGS'
mkdir -p build/RunOptimizedProdServer
ghc -O2 -threaded -i. -ibuild -iConfig -iIHP -iIHP/IDE -XGHC2021 -XOverloadedStrings -XNoImplicitPrelude -XImplicitParams -XRank2Types -XDisambiguateRecordFields -XNamedFieldPuns -XDuplicateRecordFields -XOverloadedLabels -XFlexibleContexts -XTypeSynonymInstances -XFlexibleInstances -XQuasiQuotes -XTypeFamilies -XPackageImports -XScopedTypeVariables -XRecordWildCards -XTypeApplications -XDataKinds -XInstanceSigs -XDeriveGeneric -XMultiParamTypeClasses -XTypeOperators -XDeriveDataTypeable -XMultiWayIf -XUndecidableInstances -XBlockArguments -XPartialTypeSignatures -XLambdaCase -Wno-unsafe -Wno-name-shadowing -Wno-monomorphism-restriction -Wno-safe -Wno-missing-local-signatures -Wno-missing-home-modules -XDefaultSignatures -XEmptyDataDeriving -XBangPatterns -XBlockArguments -XMultiWayIf -XFunctionalDependencies -fbyte-code -Wno-partial-type-signatures -XPartialTypeSignatures -XStandaloneDeriving -XDerivingVia -Werror=missing-fields -fwarn-incomplete-patterns -XTemplateHaskell -XDeepSubsumption -XOverloadedRecordDot -j -package-env -  +RTS -A256m -n2m -N --RTS -package ihp -rtsopts=all -funbox-strict-fields -fconstraint-solver-iterations=100 -fdicts-strict -with-rtsopts="" Main.hs -o build/bin/RunOptimizedProdServer -odir build/RunOptimizedProdServer -hidir build/RunOptimizedProdServer
ghc-9.8.4: no input files
Usage: For basic information, try the `--help' option.
make: *** [/nix/store/24c201n06yjp6bcafkd941c83r99rpmw-ihp-env-var-backwards-compat/Makefile.dist:130: build/bin/RunOptimizedProdServer] Error 1