The old Minecraft.jar launcher now fails?

[20:18:23 INFO]: Minecraft Launcher unknown (through bootstrap 5) started on windows...[20:18:23 INFO]: Minecraft Launcher unknown (through bootstrap 5) started on windows...[20:18:23 INFO]: Current time is Sep 6, 2019, 8:18:23 PM[20:18:23 INFO]: System.getProperty('os.name') == 'Windows 7'[20:18:23 INFO]: System.getProperty('os.version') == '6.1'[20:18:23 INFO]: System.getProperty('os.arch') == 'amd64'[20:18:23 INFO]: System.getProperty('java.version') == '9'[20:18:23 INFO]: System.getProperty('java.vendor') == 'Oracle Corporation'[20:18:23 INFO]: System.getProperty('sun.arch.data.model') == '64'[20:18:23 INFO]: proxy == DIRECT[20:18:23 INFO]: JFX is already initialized[20:18:24 INFO]: Refreshing local version list...[20:18:24 INFO]: Refreshing remote version list...[20:18:24 INFO]: Refresh complete.[20:18:24 INFO]: Loaded 0 profile(s); selected '(Default)'[20:18:35 INFO]: Logging in with username & password[20:18:40 INFO]: Getting syncinfo for selected version[20:18:40 INFO]: Queueing library & version downloads[20:18:40 FATAL]: Unhandled exception in thread Thread[pool-2-thread-3,5,main]com.google.gson.JsonSyntaxException: duplicate key: null at com.google.gson.internal.bind.MapTypeAdapterFactory$Adapter.read(MapTypeAdapterFactory.java:191) ~[Minecraft.jar:?] at com.google.gson.internal.bind.MapTypeAdapterFactory$Adapter.read(MapTypeAdapterFactory.java:146) ~[Minecraft.jar:?] at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.read(ReflectiveTypeAdapterFactory.java:93) ~[Minecraft.jar:?] at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:172) ~[Minecraft.jar:?] at com.google.gson.Gson.fromJson(Gson.java:795) ~[Minecraft.jar:?] at com.google.gson.Gson.fromJson(Gson.java:761) ~[Minecraft.jar:?] at com.google.gson.Gson.fromJson(Gson.java:710) ~[Minecraft.jar:?] at com.google.gson.Gson.fromJson(Gson.java:682) ~[Minecraft.jar:?] at net.minecraft.launcher.updater.RemoteVersionList.getCompleteVersion(RemoteVersionList.java:32) ~[launcher.jar:?] at net.minecraft.launcher.updater.MinecraftVersionManager.getLatestCompleteVersion(MinecraftVersionManager.java:213) ~[launcher.jar:?] at net.minecraft.launcher.updater.MinecraftVersionManager.getLatestCompleteVersion(MinecraftVersionManager.java:37) ~[launcher.jar:?] at com.mojang.launcher.game.runner.AbstractGameRunner.playGame(AbstractGameRunner.java:67) ~[launcher.jar:?] at net.minecraft.launcher.game.GameLaunchDispatcher$1.run(GameLaunchDispatcher.java:111) ~[launcher.jar:?] at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) ~[?:?] at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) ~[?:?] at java.base/java.lang.Thread.run(Unknown Source) [?:?]