After doing so, on every single world I have tried to open, including those created in the snapshot, crashes with this error message:

Completely ignored arguments: [--nativeLauncherVersion, 286]
[12:41:11] [Client thread/INFO]: Setting user: Achitect_Drone
[12:41:11] [Client thread/INFO]: (Session ID is token:245367ca4b7f4acda9d7dd4702ba402a:61070d7e1abc4bccb254c7b7af78e639)
[12:41:16] [Client thread/INFO]: LWJGL Version: 2.9.4
[12:41:16] [Client thread/INFO]: Reloading ResourceManager: Default
[12:41:17] [Sound Library Loader/INFO]: Starting up SoundSystem...
[12:41:17] [Thread-5/INFO]: Initializing LWJGL OpenAL
[12:41:17] [Thread-5/INFO]: (The LWJGL binding of OpenAL. For more information, see http://www.lwjgl.org)
[12:41:17] [Thread-5/INFO]: OpenAL initialized.
[12:41:17] [Sound Library Loader/INFO]: Sound engine started
[12:41:20] [Client thread/INFO]: Created: 1024x512 textures-atlas
[12:41:24] [Client thread/WARN]: Unable to resolve BlockEntity for ItemInstance: minecraft:shield
[12:41:27] [Server thread/INFO]: Starting integrated minecraft server version 15w41b
[12:41:27] [Server thread/INFO]: Generating keypair
[12:41:28] [Server thread/INFO]: Preparing start region for level 0
[12:41:29] [Server thread/INFO]: Preparing spawn area: 2%
[12:41:30] [Server thread/INFO]: Preparing spawn area: 31%
[12:41:31] [Server thread/INFO]: Preparing spawn area: 63%
[12:41:32] [Server thread/INFO]: Preparing spawn area: 93%
[12:41:33] [Server thread/INFO]: Changing view distance to 9, from 10
[12:41:34] [Server thread/INFO]: Achitect_Drone[local:E:985b3726] logged in with entity id 259 at (1725.545480510273, 77.99574230787404, -147.52289129977848)
[12:41:34] [Server thread/INFO]: Achitect_Drone joined the game
[12:41:35] [Server thread/INFO]: Saving and pausing game...
[12:41:35] [Server thread/INFO]: Saving chunks for level '1.9 Elytra Amp'/Overworld
[12:41:36] [Server thread/INFO]: Saving chunks for level '1.9 Elytra Amp'/Nether
[12:41:36] [Server thread/INFO]: Saving chunks for level '1.9 Elytra Amp'/The End
#

1. A fatal error has been detected by the Java Runtime Environment:
   #
2. EXCEPTION_ACCESS_VIOLATION (0xc0000005) at pc=0x00007ff9ef34125c, pid=8272, tid=8276
   #
3. JRE version: Java(TM) SE Runtime Environment (8.0_25-b18) (build 1.8.0_25-b18)
4. Java VM: Java HotSpot(TM) 64-Bit Server VM (25.25-b02 mixed mode windows-amd64 compressed oops)
5. Problematic frame:
6. C [ig8icd64.dll+0x63125c]
   #
7. Failed to write core dump. Minidumps are not enabled by default on client versions of Windows
   #
8. An error report file with more information is saved as:
9. C:\Users\Owen Mellema\AppData\Roaming\.minecraft\hs_err_pid8272.log
   #
10. If you would like to submit a bug report, please visit:
11. http://bugreport.sun.com/bugreport/crash.jsp
12. The crash happened outside the Java Virtual Machine in native code.
13. See problematic frame for where to report the bug.
    #
    AL lib: (EE) alc_cleanup: 1 device not closed
    Java HotSpot(TM) 64-Bit Server VM warning: Using incremental CMS is deprecated and will likely be removed in a future release