Example mod fails and terminates the window in seconds - 1.15.2 - Eclipse

[Bear Bear]

Hi, first off I'm completely new to all of this and I apologise if I haven't supplied the necessary information to assess my issue. 

I've been trying to follow both the getting started guide here (The forge readthedocs page.) and a guide from a website called codakid. (I'm attemping this with MC 1.15.2 using Eclipse on windows 10)

My issue is on following all the steps and attempting to launch the example mod running the RunClient command or RunBuild command everything is working until the client window pops up for a mere second or two then is terminated.

I've installed everything and run everything I've supposedly needed to and the error messages I can find leave me stumped.

Here is my "latest.log" I hope it's the log needed to highlight the issue.

[13Mar2021 17:48:42.605] [main/INFO] [cpw.mods.modlauncher.Launcher/MODLAUNCHER]: ModLauncher running: args [--gameDir, ., --launchTarget, fmluserdevclient, --fml.mcpVersion, 20200515.085601, --fml.mcVersion, 1.15.2, --fml.forgeGroup, net.minecraftforge, --fml.forgeVersion, 31.2.49, --version, MOD_DEV, --assetIndex, 1.15, --assetsDir, C:\Users\Name\.gradle\caches\forge_gradle\assets, --username, Dev, --accessToken, ????????, --userProperties, {}]
[13Mar2021 17:48:42.614] [main/INFO] [cpw.mods.modlauncher.Launcher/MODLAUNCHER]: ModLauncher 5.1.2+70+master.2845bb9 starting: java version 15.0.2 by Oracle Corporation
[13Mar2021 17:48:43.132] [main/INFO] [net.minecraftforge.fml.loading.FixSSL/CORE]: Added Lets Encrypt root certificates as additional trust
[13Mar2021 17:48:43.235] [main/INFO] [mixin/]: SpongePowered MIXIN Subsystem Version=0.8.2 Source=file:/C:/Users/Name/.gradle/caches/modules-2/files-2.1/org.spongepowered/mixin/0.8.2/1cf212283d26f706fd3074318870bebd14d2a9ed/mixin-0.8.2.jar Service=ModLauncher Env=CLIENT
[13Mar2021 17:52:19.808] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1048]: java.lang.NoClassDefFoundError: jdk/nashorn/api/scripting/NashornScriptEngineFactory
[13Mar2021 17:52:19.808] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1048]: 	at net.minecraftforge.coremod.CoreModEngine.loadCoreMod(CoreModEngine.java:48)
[13Mar2021 17:52:19.808] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1048]: 	at net.minecraftforge.coremod.CoreModProvider.addCoreMod(CoreModProvider.java:12)
[13Mar2021 17:52:19.809] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1048]: 	at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:183)
[13Mar2021 17:52:19.809] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1048]: 	at java.base/java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1625)
[13Mar2021 17:52:19.809] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1048]: 	at java.base/java.util.stream.ReferencePipeline$Head.forEach(ReferencePipeline.java:658)
[13Mar2021 17:52:19.809] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1048]: 	at java.base/java.util.stream.ReferencePipeline$7$1.accept(ReferencePipeline.java:274)
[13Mar2021 17:52:19.809] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1048]: 	at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:195)
[13Mar2021 17:52:19.810] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1048]: 	at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:195)
[13Mar2021 17:52:19.810] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1048]: 	at java.base/java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1625)
[13Mar2021 17:52:19.810] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1048]: 	at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:484)
[13Mar2021 17:52:19.810] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1048]: 	at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474)
[13Mar2021 17:52:19.810] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1048]: 	at java.base/java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:150)
[13Mar2021 17:52:19.811] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1048]: 	at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:173)
[13Mar2021 17:52:19.811] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1048]: 	at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
[13Mar2021 17:52:19.811] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1048]: 	at java.base/java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:497)
[13Mar2021 17:52:19.811] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1048]: 	at net.minecraftforge.fml.loading.LoadingModList.addCoreMods(LoadingModList.java:88)
[13Mar2021 17:52:19.811] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1048]: 	at net.minecraftforge.fml.loading.moddiscovery.ModDiscoverer.discoverMods(ModDiscoverer.java:125)
[13Mar2021 17:52:19.812] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1048]: 	at net.minecraftforge.fml.loading.FMLLoader.beginModScan(FMLLoader.java:213)
[13Mar2021 17:52:19.812] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1048]: 	at net.minecraftforge.fml.loading.FMLServiceProvider.runScan(FMLServiceProvider.java:107)
[13Mar2021 17:52:19.812] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1048]: 	at cpw.mods.modlauncher.TransformationServiceDecorator.runScan(TransformationServiceDecorator.java:111)
[13Mar2021 17:52:19.812] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1048]: 	at cpw.mods.modlauncher.TransformationServicesHandler.lambda$runScanningTransformationServices$8(TransformationServicesHandler.java:115)
[13Mar2021 17:52:19.812] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1048]: 	at java.base/java.util.stream.ReferencePipeline$7$1.accept(ReferencePipeline.java:271)
[13Mar2021 17:52:19.813] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1048]: 	at java.base/java.util.HashMap$ValueSpliterator.forEachRemaining(HashMap.java:1766)
[13Mar2021 17:52:19.813] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1048]: 	at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:484)
[13Mar2021 17:52:19.813] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1048]: 	at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474)
[13Mar2021 17:52:19.813] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1048]: 	at java.base/java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:913)
[13Mar2021 17:52:19.813] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1048]: 	at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
[13Mar2021 17:52:19.814] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1048]: 	at java.base/java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:578)
[13Mar2021 17:52:19.814] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1048]: 	at cpw.mods.modlauncher.TransformationServicesHandler.runScanningTransformationServices(TransformationServicesHandler.java:116)
[13Mar2021 17:52:19.814] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1048]: 	at cpw.mods.modlauncher.TransformationServicesHandler.initializeTransformationServices(TransformationServicesHandler.java:63)
[13Mar2021 17:52:19.814] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1048]: 	at cpw.mods.modlauncher.Launcher.run(Launcher.java:75)
[13Mar2021 17:52:19.814] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1048]: 	at cpw.mods.modlauncher.Launcher.main(Launcher.java:65)
[13Mar2021 17:52:19.815] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1048]: 	at net.minecraftforge.userdev.LaunchTesting.main(LaunchTesting.java:105)
[13Mar2021 17:52:19.815] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1057]: Caused by: java.lang.ClassNotFoundException: jdk.nashorn.api.scripting.NashornScriptEngineFactory
[13Mar2021 17:52:19.815] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1057]: 	at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:606)
[13Mar2021 17:52:19.816] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1057]: 	at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:168)
[13Mar2021 17:52:19.816] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1057]: 	at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:522)
[13Mar2021 17:52:19.816] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1057]: 	... 33 more

 

I've tried installing and uninstalling both JDK 15 and 14.0.2 in case the issue lied there but no progress has been made. 

Again I'm using Eclipse on Windows 10 loading MC 1.15.2 and just trying to run the example mod following the procedures listed on the readthedocs page. 

[Bear Bear]

I've realised now I may have posted this in the from section of the forums - However I've 'fixed' the problem by simply using intJ instead of Eclipse. No idea what went wrong with Eclipse but RunClient works just fine on IntJ.