com.google.gson let me couldn't play minecraft!

at com.google.gson.Gson.fromJson(Gson.java:818) ~[Mineshafter-launcher.jar:?]
	at com.google.gson.Gson.fromJson(Gson.java:768) ~[Mineshafter-launcher.jar:?]
	at com.google.gson.Gson.fromJson(Gson.java:717) ~[Mineshafter-launcher.jar:?]
	at com.google.gson.Gson.fromJson(Gson.java:689) ~[Mineshafter-launcher.jar:?]
	at net.minecraft.launcher.game.MinecraftGameRunner.reconstructAssets(MinecraftGameRunner.java:249) ~[launcher_mcpatched.jar:?]
	at net.minecraft.launcher.game.MinecraftGameRunner.launchGame(MinecraftGameRunner.java:115) ~[launcher_mcpatched.jar:?]
	at com.mojang.launcher.game.runner.AbstractGameRunner.onDownloadJobFinished(AbstractGameRunner.java:177) [launcher_mcpatched.jar:?]
	at com.mojang.launcher.updater.download.DownloadJob.popAndDownload(DownloadJob.java:122) [launcher_mcpatched.jar:?]
	at com.mojang.launcher.updater.download.DownloadJob.access$000(DownloadJob.java:12) [launcher_mcpatched.jar:?]
	at com.mojang.launcher.updater.download.DownloadJob$1.run(DownloadJob.java:86) [launcher_mcpatched.jar:?]
	at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) [?:1.7.0_60]
	at java.util.concurrent.FutureTask.run(Unknown Source) [?:1.7.0_60]
	at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) [?:1.7.0_60]
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) [?:1.7.0_60]
	at java.lang.Thread.run(Unknown Source) [?:1.7.0_60]
Caused by: com.google.gson.stream.MalformedJsonException: Unterminated string at line 1281 column 40
	at com.google.gson.stream.JsonReader.syntaxError(JsonReader.java:1505) ~[Mineshafter-launcher.jar:?]
	at com.google.gson.stream.JsonReader.nextQuotedValue(JsonReader.java:1006) ~[Mineshafter-launcher.jar:?]
	at com.google.gson.stream.JsonReader.nextString(JsonReader.java:811) ~[Mineshafter-launcher.jar:?]
	at com.google.gson.internal.bind.TypeAdapters$13.read(TypeAdapters.java:358) ~[Mineshafter-launcher.jar:?]
	at com.google.gson.internal.bind.TypeAdapters$13.read(TypeAdapters.java:1) ~[Mineshafter-launcher.jar:?]
	at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.read(ReflectiveTypeAdapterFactory.java:93) ~[Mineshafter-launcher.jar:?]
	at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:172) ~[Mineshafter-launcher.jar:?]
	at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.read(TypeAdapterRuntimeTypeWrapper.java:40) ~[Mineshafter-launcher.jar:?]
	at com.google.gson.internal.bind.MapTypeAdapterFactory$Adapter.read(MapTypeAdapterFactory.java:187) ~[Mineshafter-launcher.jar:?]
	at com.google.gson.internal.bind.MapTypeAdapterFactory$Adapter.read(MapTypeAdapterFactory.java:1) ~[Mineshafter-launcher.jar:?]
	at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.read(ReflectiveTypeAdapterFactory.java:93) ~[Mineshafter-launcher.jar:?]
	at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:172) ~[Mineshafter-launcher.jar:?]
	at com.google.gson.Gson.fromJson(Gson.java:803) ~[Mineshafter-launcher.jar:?]
	... 14 more