[13:00:23] [Server thread/ERROR] [Sponge/]: Error occurred while executing command 'minecraft:tp @p 251 21 -504' for source net.minecraft.tileentity.TileEntityCommandBlock@d4ca7d2: net.minecraft.tileentity.TileEntityCommandBlock$1 cannot be cast to org.spongepowered.api.util.command.CommandSource
java.lang.ClassCastException: net.minecraft.tileentity.TileEntityCommandBlock$1 cannot be cast to org.spongepowered.api.util.command.CommandSource
        at net.minecraft.command.PlayerSelector.redirectCanUseCommand(SourceFile:40) ~[ah.class:?]
        at net.minecraft.command.PlayerSelector.func_179656_b(SourceFile:110) ~[ah.class:?]
        at net.minecraft.command.PlayerSelector.func_179652_a(SourceFile:88) ~[ah.class:?]
        at net.minecraft.command.CommandBase.func_175759_a(SourceFile:172) ~[z.class:?]
        at net.minecraft.command.CommandBase.func_175768_b(SourceFile:167) ~[z.class:?]
        at net.minecraft.command.server.CommandTeleport.func_71515_b(SourceFile:44) ~[cw.class:?]
        at net.minecraft.command.CommandHandler.func_175786_a(CommandHandler.java:108) ~[ab.class:?]
        at org.spongepowered.common.command.MinecraftCommandWrapper.tryExecute(MinecraftCommandWrapper.java:127) ~[MinecraftCommandWrapper.class:1.8-1499-2.1DEV-634+spongeproject-ci-b634.git-38a5fb2d71d332808348526a2a8c3beffb2c18c4]
        at org.spongepowered.common.command.MinecraftCommandWrapper.process(MinecraftCommandWrapper.java:113) ~[MinecraftCommandWrapper.class:1.8-1499-2.1DEV-634+spongeproject-ci-b634.git-38a5fb2d71d332808348526a2a8c3beffb2c18c4]
        at org.spongepowered.api.util.command.dispatcher.SimpleDispatcher.process(SimpleDispatcher.java:345) ~[SimpleDispatcher.class:1.8-1499-2.1DEV-634+spongeproject-ci-b634.git-38a5fb2d71d332808348526a2a8c3beffb2c18c4]
        at org.spongepowered.api.service.command.SimpleCommandService.process(SimpleCommandService.java:251) [SimpleCommandService.class:1.8-1499-2.1DEV-634+spongeproject-ci-b634.git-38a5fb2d71d332808348526a2a8c3beffb2c18c4]
        at net.minecraft.command.ServerCommandManager.func_71556_a(SourceFile:80) [cl.class:?]
        at net.minecraft.command.server.CommandBlockLogic.func_145755_a(SourceFile:97) [aqf.class:?]
        at net.minecraft.block.BlockCommandBlock.func_180650_b(SourceFile:53) [auo.class:?]
        at net.minecraft.world.WorldServer.func_72955_a(WorldServer.java:638) [qt.class:?]
        at net.minecraft.world.WorldServer.func_72835_b(WorldServer.java:219) [qt.class:?]
        at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:693) [MinecraftServer.class:?]
        at net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:364) [po.class:?]
        at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:598) [MinecraftServer.class:?]
        at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:478) [MinecraftServer.class:?]
        at java.lang.Thread.run(Unknown Source) [?:1.8.0_60]