Mod Version: [Fabric 1.20.x] 1.2.0
Mod Loader: Fabric

Description:
Dev environment, datagen isues

To Reproduce:
Steps to reproduce the behavior:

1. Add modRuntimeOnly("curse.maven:deeperdarker-659011:4715721") {transitive false} to build.gradle
2. Run datagen

Error
java.lang.RuntimeException: Could not execute entrypoint stage 'main' due to errors, provided by 'deeperdarker'!
at net.fabricmc.loader.impl.entrypoint.EntrypointUtils.lambda$invoke0$0(EntrypointUtils.java:51) ~[fabric-loader-0.14.22.jar:?]
at net.fabricmc.loader.impl.util.ExceptionUtil.gatherExceptions(ExceptionUtil.java:33) ~[fabric-loader-0.14.22.jar:?]
at net.fabricmc.loader.impl.entrypoint.EntrypointUtils.invoke0(EntrypointUtils.java:49) ~[fabric-loader-0.14.22.jar:?]
at net.fabricmc.loader.impl.entrypoint.EntrypointUtils.invoke(EntrypointUtils.java:35) ~[fabric-loader-0.14.22.jar:?]
at net.fabricmc.loader.impl.game.minecraft.Hooks.startServer(Hooks.java:62) ~[fabric-loader-0.14.22.jar:?]
at net.minecraft.server.Main.main(Main.java:112) ~[minecraft-merged-project-root-1.20.1-net.fabricmc.yarn.1_20_1.1.20.1+build.10-v2.jar:?]
at net.fabricmc.loader.impl.game.minecraft.MinecraftGameProvider.launch(MinecraftGameProvider.java:468) ~[fabric-loader-0.14.22.jar:?]
at net.fabricmc.loader.impl.launch.knot.Knot.launch(Knot.java:74) ~[fabric-loader-0.14.22.jar:?]
at net.fabricmc.loader.impl.launch.knot.KnotServer.main(KnotServer.java:23) ~[fabric-loader-0.14.22.jar:?]
at net.fabricmc.devlaunchinjector.Main.main(Main.java:86) ~[dev-launch-injector-0.2.1+build.8.jar:?]
Caused by: java.lang.NoClassDefFoundError: net/kyrptonaught/customportalapi/CustomPortalBlock
at java.lang.ClassLoader.defineClass1(Native Method) ~[?:?]
at java.lang.ClassLoader.defineClass(ClassLoader.java:1012) ~[?:?]
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:150) ~[?:?]
at net.fabricmc.loader.impl.launch.knot.KnotClassLoader.defineClassFwd(KnotClassLoader.java:153) ~[fabric-loader-0.14.22.jar:?]
at net.fabricmc.loader.impl.launch.knot.KnotClassDelegate.tryLoadClass(KnotClassDelegate.java:355) ~[fabric-loader-0.14.22.jar:?]
at net.fabricmc.loader.impl.launch.knot.KnotClassDelegate.loadClass(KnotClassDelegate.java:218) ~[fabric-loader-0.14.22.jar:?]
at net.fabricmc.loader.impl.launch.knot.KnotClassLoader.loadClass(KnotClassLoader.java:112) ~[fabric-loader-0.14.22.jar:?]
at java.lang.ClassLoader.loadClass(ClassLoader.java:520) ~[?:?]
at com.kyanite.deeperdarker.content.DDItems.(DDItems.java:22) ~[deeperdarker-659011-4715721.jar:?]
at com.kyanite.deeperdarker.DeeperDarker.onInitialize(DeeperDarker.java:35) ~[deeperdarker-659011-4715721.jar:?]
at net.fabricmc.loader.impl.entrypoint.EntrypointUtils.invoke0(EntrypointUtils.java:47) ~[fabric-loader-0.14.22.jar:?]
... 7 more
Caused by: java.lang.ClassNotFoundException: net.kyrptonaught.customportalapi.CustomPortalBlock
at jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:641) ~[?:?]
at java.lang.ClassLoader.loadClass(ClassLoader.java:520) ~[?:?]
at net.fabricmc.loader.impl.launch.knot.KnotClassDelegate.loadClass(KnotClassDelegate.java:226) ~[fabric-loader-0.14.22.jar:?]
at net.fabricmc.loader.impl.launch.knot.KnotClassLoader.loadClass(KnotClassLoader.java:112) ~[fabric-loader-0.14.22.jar:?]
at java.lang.ClassLoader.loadClass(ClassLoader.java:520) ~[?:?]
at java.lang.ClassLoader.defineClass1(Native Method) ~[?:?]
at java.lang.ClassLoader.defineClass(ClassLoader.java:1012) ~[?:?]
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:150) ~[?:?]
at net.fabricmc.loader.impl.launch.knot.KnotClassLoader.defineClassFwd(KnotClassLoader.java:153) ~[fabric-loader-0.14.22.jar:?]
at net.fabricmc.loader.impl.launch.knot.KnotClassDelegate.tryLoadClass(KnotClassDelegate.java:355) ~[fabric-loader-0.14.22.jar:?]
at net.fabricmc.loader.impl.launch.knot.KnotClassDelegate.loadClass(KnotClassDelegate.java:218) ~[fabric-loader-0.14.22.jar:?]
at net.fabricmc.loader.impl.launch.knot.KnotClassLoader.loadClass(KnotClassLoader.java:112) ~[fabric-loader-0.14.22.jar:?]
at java.lang.ClassLoader.loadClass(ClassLoader.java:520) ~[?:?]
at com.kyanite.deeperdarker.content.DDItems.(DDItems.java:22) ~[deeperdarker-659011-4715721.jar:?]
at com.kyanite.deeperdarker.DeeperDarker.onInitialize(DeeperDarker.java:35) ~[deeperdarker-659011-4715721.jar:?]
at net.fabricmc.loader.impl.entrypoint.EntrypointUtils.invoke0(EntrypointUtils.java:47) ~[fabric-loader-0.14.22.jar:?]
... 7 more

I believe you need to add Custom Portal API to your build.gradle:

modImplementation 'net.kyrptonaught:customportalapi:<version>'
include 'net.kyrptonaught:customportalapi:<version>'