RPC error

/Bad_Dobby disconnecting: RPC Error in CLIENT_ChangeSkin: Object reference not set to an instance of an object.   at WallpaperPlanner.%557f2fcc625b1825e8a3c56cdc355adb4e86f9db (BaseEntity+%fa074292ba40a9851d408ff9e2153d6aad55e4df %38de41afb923576aa00765babc208f80e663a553) [0x00000] in <00000000000000000000000000000000>:0     at WallpaperPlanner.%5d824f33dad022d59d102662f4cc35def2e13ece (BasePlayer %881ac69e91e151b5d44e28d625b584d3f1c8a3b2, System.UInt32 %7240cbe6dcf87806bd402435ee3b7272aa8dd745, %f5ecb3c208ec3e73bbdf2e0939c61c3d8ae69cc5 %38de41afb923576aa00765babc208f80e663a553) [0x00000] in <00000000000000000000000000000000>:0     at Client.%c523d728d4b2394721961994b834ed8e2c3a393f (%f5ecb3c208ec3e73bbdf2e0939c61c3d8ae69cc5 %e3eb193a62baf6a9ea5c054089065fba06f67308) [0x00000] in <00000000000000000000000000000000>:0     at Client.%95a8431be122f354d89a725e49ce57b788c1e9ee (%f5ecb3c208ec3e73bbdf2e0939c61c3d8ae69cc5 %e3eb193a62baf6a9ea5c054089065fba06f67308) [0x00000] in <00000000000000000000000000000000>:0     at %7b7b31efc18b33db934935eda373f1631b1d3630.%648792985795ae82ac06ee2d6d8f21c4025c63c6 (%0397e1ab942a786572a11878f966468cb66bda09 %160ef7babcc77b1ed29001a172df456e3f64028f) [0x00000] in <00000000000000000000000000000000>:0     at %0ca75a3cd4ccebccdbf485120559c457df708f43.%a06718feb44e4946efefb2996d53a170c917fbfe () [0x00000] in <00000000000000000000000000000000>:0     at Client.Update () [0x00000] in <00000000000000000000000000000000>:0 


Can you offer any insight to the cause of this while use wallpaperplanner?