Vanilla launcher downloads its own Java version (out dated) to use for you inside the . Minecraft folder. GDLauncher does not do ether of these things. That is why you need to manually download Java 8 ...

java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: Module threw exception at net.imagej.legacy.LegacyService.runLegacyCompatibleCommand ...