Hello Mojang Team,
I paste the command

/setblock ~ ~1 ~ wall_sign 2 replace {Text1:"[{text:\"[Kit]\",color:\"dark_gray\",bold:\"true\",clickEvent:{action:\"open_url\",value:\"scoreboard players set @p kit 1\"}}]",Text2:"[

]"}

in a command block and activated it.
This command should place a sign at the coordinates ~ ~1 ~ facing North.

I used Version 15w35e

What actually happened was...:
My Client crashed but the Server was Okay.
When I joined, it crashed again.
I had to remove the Title Entity with MCedit to fix this bug.

Steps to Reproduce:
1. Place a command block on a wall facing South.
2. Paste the command above in the command block.
3. Activate it.