The exact error that I am getting is:

[01:43:36 ERROR]: Unexpected exception refreshing profile list
com.google.gson.JsonSyntaxException: duplicate key: null
at com.google.gson.internal.bind.MapTypeAdapterFactory$Adapter.read(MapTypeAdapterFactory.java:190) ~[launcher.jar:1.6.91]
at com.google.gson.internal.bind.MapTypeAdapterFactory$Adapter.read(MapTypeAdapterFactory.java:145) ~[launcher.jar:1.6.91]
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.read(ReflectiveTypeAdapterFactory.java:93) ~[launcher.jar:1.6.91]
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:172) ~[launcher.jar:1.6.91]
at com.google.gson.Gson.fromJson(Gson.java:803) ~[launcher.jar:1.6.91]
at com.google.gson.Gson.fromJson(Gson.java:768) ~[launcher.jar:1.6.91]
at com.google.gson.Gson.fromJson(Gson.java:717) ~[launcher.jar:1.6.91]
at com.google.gson.Gson.fromJson(Gson.java:689) ~[launcher.jar:1.6.91]
at net.minecraft.launcher.updater.RemoteVersionList.getCompleteVersion(RemoteVersionList.java:32) ~[launcher.jar:1.6.91]
at net.minecraft.launcher.updater.MinecraftVersionManager.getLatestCompleteVersion(MinecraftVersionManager.java:213) ~[launcher.jar:1.6.91]
at net.minecraft.launcher.updater.CompleteMinecraftVersion.resolve(CompleteMinecraftVersion.java:268) ~[launcher.jar:1.6.91]
at net.minecraft.launcher.updater.CompleteMinecraftVersion.resolve(CompleteMinecraftVersion.java:255) ~[launcher.jar:1.6.91]
at net.minecraft.launcher.updater.MinecraftVersionManager.getVersionSyncInfo(MinecraftVersionManager.java:171) ~[launcher.jar:1.6.91]
at net.minecraft.launcher.updater.MinecraftVersionManager.getVersions(MinecraftVersionManager.java:105) ~[launcher.jar:1.6.91]
at net.minecraft.launcher.game.GameLaunchDispatcher.getStatus(GameLaunchDispatcher.java:35) ~[launcher.jar:1.6.91]
at net.minecraft.launcher.ui.bottombar.PlayButtonPanel.checkState(PlayButtonPanel.java:94) ~[launcher.jar:1.6.91]
at net.minecraft.launcher.ui.bottombar.PlayButtonPanel.onProfilesRefreshed(PlayButtonPanel.java:90) ~[launcher.jar:1.6.91]
at net.minecraft.launcher.profile.ProfileManager.fireRefreshEvent(ProfileManager.java:100) ~[launcher.jar:1.6.91]
at net.minecraft.launcher.profile.ProfileManager.loadProfiles(ProfileManager.java:88) ~[launcher.jar:1.6.91]
at net.minecraft.launcher.Launcher$2.run(Launcher.java:183) [launcher.jar:1.6.91]
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [?:1.8.0_251]
at java.util.concurrent.FutureTask.run(FutureTask.java:266) [?:1.8.0_251]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [?:1.8.0_251]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [?:1.8.0_251]
at java.lang.Thread.run(Thread.java:748) [?:1.8.0_251]
[01:43:36 INFO]: Refreshing auth...
[01:43:36 INFO]: Logging in with access token
[01:43:36 FATAL]: Unhandled exception in thread Thread[AWT-EventQueue-0,6,main]
com.google.gson.JsonSyntaxException: duplicate key: null
at com.google.gson.internal.bind.MapTypeAdapterFactory$Adapter.read(MapTypeAdapterFactory.java:190) ~[launcher.jar:1.6.91]
at com.google.gson.internal.bind.MapTypeAdapterFactory$Adapter.read(MapTypeAdapterFactory.java:145) ~[launcher.jar:1.6.91]
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.read(ReflectiveTypeAdapterFactory.java:93) ~[launcher.jar:1.6.91]
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:172) ~[launcher.jar:1.6.91]
at com.google.gson.Gson.fromJson(Gson.java:803) ~[launcher.jar:1.6.91]
at com.google.gson.Gson.fromJson(Gson.java:768) ~[launcher.jar:1.6.91]
at com.google.gson.Gson.fromJson(Gson.java:717) ~[launcher.jar:1.6.91]
at com.google.gson.Gson.fromJson(Gson.java:689) ~[launcher.jar:1.6.91]
at net.minecraft.launcher.updater.RemoteVersionList.getCompleteVersion(RemoteVersionList.java:32) ~[launcher.jar:1.6.91]
at net.minecraft.launcher.updater.MinecraftVersionManager.getLatestCompleteVersion(MinecraftVersionManager.java:213) ~[launcher.jar:1.6.91]
at net.minecraft.launcher.updater.CompleteMinecraftVersion.resolve(CompleteMinecraftVersion.java:268) ~[launcher.jar:1.6.91]
at net.minecraft.launcher.updater.CompleteMinecraftVersion.resolve(CompleteMinecraftVersion.java:255) ~[launcher.jar:1.6.91]
at net.minecraft.launcher.updater.MinecraftVersionManager.getVersionSyncInfo(MinecraftVersionManager.java:171) ~[launcher.jar:1.6.91]
at net.minecraft.launcher.updater.MinecraftVersionManager.getVersions(MinecraftVersionManager.java:105) ~[launcher.jar:1.6.91]
at net.minecraft.launcher.ui.bottombar.PlayerInfoPanel.checkState(PlayerInfoPanel.java:96) ~[launcher.jar:1.6.91]
at net.minecraft.launcher.ui.bottombar.PlayerInfoPanel$2.run(PlayerInfoPanel.java:78) ~[launcher.jar:1.6.91]
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:311) ~[?:1.8.0_251]
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:758) ~[?:1.8.0_251]
at java.awt.EventQueue.access$500(EventQueue.java:97) ~[?:1.8.0_251]
at java.awt.EventQueue$3.run(EventQueue.java:709) ~[?:1.8.0_251]
at java.awt.EventQueue$3.run(EventQueue.java:703) ~[?:1.8.0_251]
at java.security.AccessController.doPrivileged(Native Method) ~[?:1.8.0_251]
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:74) ~[?:1.8.0_251]
at java.awt.EventQueue.dispatchEvent(EventQueue.java:728) ~[?:1.8.0_251]
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:205) [?:1.8.0_251]
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116) [?:1.8.0_251]
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105) [?:1.8.0_251]
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101) [?:1.8.0_251]
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93) [?:1.8.0_251]
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82) [?:1.8.0_251]
[01:43:37 FATAL]: Unhandled exception in thread Thread[AWT-EventQueue-0,6,main]
com.google.gson.JsonSyntaxException: duplicate key: null
at com.google.gson.internal.bind.MapTypeAdapterFactory$Adapter.read(MapTypeAdapterFactory.java:190) ~[launcher.jar:1.6.91]
at com.google.gson.internal.bind.MapTypeAdapterFactory$Adapter.read(MapTypeAdapterFactory.java:145) ~[launcher.jar:1.6.91]
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.read(ReflectiveTypeAdapterFactory.java:93) ~[launcher.jar:1.6.91]
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:172) ~[launcher.jar:1.6.91]
at com.google.gson.Gson.fromJson(Gson.java:803) ~[launcher.jar:1.6.91]
at com.google.gson.Gson.fromJson(Gson.java:768) ~[launcher.jar:1.6.91]
at com.google.gson.Gson.fromJson(Gson.java:717) ~[launcher.jar:1.6.91]
at com.google.gson.Gson.fromJson(Gson.java:689) ~[launcher.jar:1.6.91]
at net.minecraft.launcher.updater.RemoteVersionList.getCompleteVersion(RemoteVersionList.java:32) ~[launcher.jar:1.6.91]
at net.minecraft.launcher.updater.MinecraftVersionManager.getLatestCompleteVersion(MinecraftVersionManager.java:213) ~[launcher.jar:1.6.91]
at net.minecraft.launcher.updater.CompleteMinecraftVersion.resolve(CompleteMinecraftVersion.java:268) ~[launcher.jar:1.6.91]
at net.minecraft.launcher.updater.CompleteMinecraftVersion.resolve(CompleteMinecraftVersion.java:255) ~[launcher.jar:1.6.91]
at net.minecraft.launcher.updater.MinecraftVersionManager.getVersionSyncInfo(MinecraftVersionManager.java:171) ~[launcher.jar:1.6.91]
at net.minecraft.launcher.updater.MinecraftVersionManager.getVersions(MinecraftVersionManager.java:105) ~[launcher.jar:1.6.91]
at net.minecraft.launcher.ui.bottombar.PlayerInfoPanel.checkState(PlayerInfoPanel.java:96) ~[launcher.jar:1.6.91]
at net.minecraft.launcher.ui.bottombar.PlayerInfoPanel$2.run(PlayerInfoPanel.java:78) ~[launcher.jar:1.6.91]
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:311) ~[?:1.8.0_251]
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:758) ~[?:1.8.0_251]
at java.awt.EventQueue.access$500(EventQueue.java:97) ~[?:1.8.0_251]
at java.awt.EventQueue$3.run(EventQueue.java:709) ~[?:1.8.0_251]
at java.awt.EventQueue$3.run(EventQueue.java:703) ~[?:1.8.0_251]
at java.security.AccessController.doPrivileged(Native Method) ~[?:1.8.0_251]
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:74) ~[?:1.8.0_251]
at java.awt.EventQueue.dispatchEvent(EventQueue.java:728) ~[?:1.8.0_251]
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:205) [?:1.8.0_251]
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116) [?:1.8.0_251]
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105) [?:1.8.0_251]
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101) [?:1.8.0_251]
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93) [?:1.8.0_251]
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82) [?:1.8.0_251]
[01:43:37 ERROR]: Unhandled exception in executor com.mojang.launcher.updater.ExceptionalThreadPoolExecutor$ExceptionalFutureTask@3240028c
java.util.concurrent.ExecutionException: com.google.gson.JsonSyntaxException: duplicate key: null
at java.util.concurrent.FutureTask.report(FutureTask.java:122) ~[?:1.8.0_251]
at java.util.concurrent.FutureTask.get(FutureTask.java:192) ~[?:1.8.0_251]
at com.mojang.launcher.updater.ExceptionalThreadPoolExecutor$ExceptionalFutureTask.done(ExceptionalThreadPoolExecutor.java:58) [launcher.jar:1.6.91]
at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:384) [?:1.8.0_251]
at java.util.concurrent.FutureTask.setException(FutureTask.java:251) [?:1.8.0_251]
at java.util.concurrent.FutureTask.run(FutureTask.java:271) [?:1.8.0_251]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [?:1.8.0_251]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [?:1.8.0_251]
at java.lang.Thread.run(Thread.java:748) [?:1.8.0_251]
Caused by: com.google.gson.JsonSyntaxException: duplicate key: null
at com.google.gson.internal.bind.MapTypeAdapterFactory$Adapter.read(MapTypeAdapterFactory.java:190) ~[launcher.jar:1.6.91]
at com.google.gson.internal.bind.MapTypeAdapterFactory$Adapter.read(MapTypeAdapterFactory.java:145) ~[launcher.jar:1.6.91]
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.read(ReflectiveTypeAdapterFactory.java:93) ~[launcher.jar:1.6.91]
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:172) ~[launcher.jar:1.6.91]
at com.google.gson.Gson.fromJson(Gson.java:803) ~[launcher.jar:1.6.91]
at com.google.gson.Gson.fromJson(Gson.java:768) ~[launcher.jar:1.6.91]
at com.google.gson.Gson.fromJson(Gson.java:717) ~[launcher.jar:1.6.91]
at com.google.gson.Gson.fromJson(Gson.java:689) ~[launcher.jar:1.6.91]
at net.minecraft.launcher.updater.RemoteVersionList.getCompleteVersion(RemoteVersionList.java:32) ~[launcher.jar:1.6.91]
at net.minecraft.launcher.updater.MinecraftVersionManager.getLatestCompleteVersion(MinecraftVersionManager.java:213) ~[launcher.jar:1.6.91]
at net.minecraft.launcher.updater.CompleteMinecraftVersion.resolve(CompleteMinecraftVersion.java:268) ~[launcher.jar:1.6.91]
at net.minecraft.launcher.updater.CompleteMinecraftVersion.resolve(CompleteMinecraftVersion.java:255) ~[launcher.jar:1.6.91]
at net.minecraft.launcher.updater.MinecraftVersionManager.getVersionSyncInfo(MinecraftVersionManager.java:171) ~[launcher.jar:1.6.91]
at net.minecraft.launcher.updater.MinecraftVersionManager.getVersions(MinecraftVersionManager.java:105) ~[launcher.jar:1.6.91]
at net.minecraft.launcher.game.GameLaunchDispatcher.getStatus(GameLaunchDispatcher.java:35) ~[launcher.jar:1.6.91]
at net.minecraft.launcher.ui.bottombar.PlayButtonPanel.checkState(PlayButtonPanel.java:94) ~[launcher.jar:1.6.91]
at net.minecraft.launcher.ui.bottombar.PlayButtonPanel.onProfilesRefreshed(PlayButtonPanel.java:90) ~[launcher.jar:1.6.91]
at net.minecraft.launcher.profile.ProfileManager.fireRefreshEvent(ProfileManager.java:100) ~[launcher.jar:1.6.91]
at net.minecraft.launcher.Launcher.ensureLoggedIn(Launcher.java:265) ~[launcher.jar:1.6.91]
at net.minecraft.launcher.Launcher$2.run(Launcher.java:213) ~[launcher.jar:1.6.91]
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) ~[?:1.8.0_251]
at java.util.concurrent.FutureTask.run(FutureTask.java:266) ~[?:1.8.0_251]
... 3 more