Exception Upgrading 1.7.10 World

[19:14:31] [Client thread/ERROR]: Something went wrong upgrading!
java.lang.RuntimeException: aer$b@38bb297
	at wo.c(SourceFile:152) ~[18w19b.jar:?]
	at wo$d.b(SourceFile:85) ~[18w19b.jar:?]
	at wo.c(SourceFile:148) ~[18w19b.jar:?]
	at xg.e(SourceFile:76) ~[18w19b.jar:?]
	at xg.f(SourceFile:85) ~[18w19b.jar:?]
	at zu.a(SourceFile:126) ~[18w19b.jar:?]
	at xi.a(SourceFile:63) ~[18w19b.jar:?]
	at xi$a.apply(SourceFile:110) ~[18w19b.jar:?]
	at xq$a.a(SourceFile:83) ~[18w19b.jar:?]
	at wo.a(SourceFile:136) ~[18w19b.jar:?]
	at wo$d.b(SourceFile:85) ~[18w19b.jar:?]
	at wo.b(SourceFile:136) ~[18w19b.jar:?]
	at xq$a.a(SourceFile:114) ~[18w19b.jar:?]
	at xq$a.a(SourceFile:83) ~[18w19b.jar:?]
	at wo.a(SourceFile:136) ~[18w19b.jar:?]
	at wo$d.b(SourceFile:85) ~[18w19b.jar:?]
	at wo.b(SourceFile:136) ~[18w19b.jar:?]
	at xq$a.a(SourceFile:114) ~[18w19b.jar:?]
	at xq$a.a(SourceFile:83) ~[18w19b.jar:?]
	at wo.a(SourceFile:136) ~[18w19b.jar:?]
	at wo$d.b(SourceFile:85) ~[18w19b.jar:?]
	at wo.b(SourceFile:136) ~[18w19b.jar:?]
	at xq$a.a(SourceFile:114) ~[18w19b.jar:?]
	at xq$a.a(SourceFile:83) ~[18w19b.jar:?]
	at wo.a(SourceFile:136) ~[18w19b.jar:?]
	at wo$d.b(SourceFile:85) ~[18w19b.jar:?]
	at wo.b(SourceFile:136) ~[18w19b.jar:?]
	at xq$a.a(SourceFile:114) ~[18w19b.jar:?]
	at xq$a.a(SourceFile:83) ~[18w19b.jar:?]
	at aao.b(SourceFile:26) ~[18w19b.jar:?]
	at aap.a(SourceFile:47) ~[18w19b.jar:?]
	at aao.b(SourceFile:26) ~[18w19b.jar:?]
	at aao.b(SourceFile:26) ~[18w19b.jar:?]
	at aao.b(SourceFile:26) ~[18w19b.jar:?]
	at aao.b(SourceFile:26) ~[18w19b.jar:?]
	at aao.b(SourceFile:26) ~[18w19b.jar:?]
	at aao.b(SourceFile:26) ~[18w19b.jar:?]
	at aao.b(SourceFile:26) ~[18w19b.jar:?]
	at aao.b(SourceFile:26) ~[18w19b.jar:?]
	at aao.b(SourceFile:26) ~[18w19b.jar:?]
	at aao.b(SourceFile:26) ~[18w19b.jar:?]
	at xq$a.a(SourceFile:103) ~[18w19b.jar:?]
	at acd.a(SourceFile:22) ~[18w19b.jar:?]
	at xq$a.a(SourceFile:104) ~[18w19b.jar:?]
	at wo.a(SourceFile:136) ~[18w19b.jar:?]
	at wo$d.b(SourceFile:85) ~[18w19b.jar:?]
	at wo.b(SourceFile:136) ~[18w19b.jar:?]
	at xq$a.a(SourceFile:114) ~[18w19b.jar:?]
	at xq$a.a(SourceFile:83) ~[18w19b.jar:?]
	at xq$a.b(SourceFile:91) ~[18w19b.jar:?]
	at xq$a.a(SourceFile:83) ~[18w19b.jar:?]
	at aao.b(SourceFile:26) ~[18w19b.jar:?]
	at xq$a.a(SourceFile:83) ~[18w19b.jar:?]
	at xq$a.b(SourceFile:91) ~[18w19b.jar:?]
	at xq$a.a(SourceFile:83) ~[18w19b.jar:?]
	at wo.a(SourceFile:136) ~[18w19b.jar:?]
	at wo$d.b(SourceFile:85) ~[18w19b.jar:?]
	at wo.b(SourceFile:136) ~[18w19b.jar:?]
	at xq$a.a(SourceFile:114) ~[18w19b.jar:?]
	at xq$a.a(SourceFile:83) ~[18w19b.jar:?]
	at xq$a.b(SourceFile:91) ~[18w19b.jar:?]
	at xq$a.a(SourceFile:83) ~[18w19b.jar:?]
	at xq$a.a(SourceFile:83) ~[18w19b.jar:?]
	at xq$a.b(SourceFile:91) ~[18w19b.jar:?]
	at xq$a.a(SourceFile:83) ~[18w19b.jar:?]
	at aao.b(SourceFile:26) ~[18w19b.jar:?]
	at aao.b(SourceFile:26) ~[18w19b.jar:?]
	at aao.b(SourceFile:26) ~[18w19b.jar:?]
	at aao.b(SourceFile:26) ~[18w19b.jar:?]
	at aao.b(SourceFile:26) ~[18w19b.jar:?]
	at aao.b(SourceFile:26) ~[18w19b.jar:?]
	at aer.a(SourceFile:137) ~[18w19b.jar:?]
	at aer.a(SourceFile:128) ~[18w19b.jar:?]
	at java.util.Optional.map(Optional.java:215) ~[?:1.8.0_171]
	at aer.a(SourceFile:127) ~[18w19b.jar:?]
	at java.util.Optional.flatMap(Optional.java:241) ~[?:1.8.0_171]
	at aer.a(SourceFile:126) ~[18w19b.jar:?]
	at xm.a(SourceFile:37) ~[18w19b.jar:?]
	at xl.a(SourceFile:14) ~[18w19b.jar:?]
	at cdy.a(SourceFile:94) ~[18w19b.jar:?]
	at cdy.c(SourceFile:76) ~[18w19b.jar:?]
	at cdv.b(SourceFile:67) ~[18w19b.jar:?]
	at cog.g(SourceFile:35) ~[18w19b.jar:?]
	at cog.<init>(SourceFile:27) ~[18w19b.jar:?]
	at coe.c(SourceFile:48) ~[18w19b.jar:?]
	at clh.a(SourceFile:311) ~[18w19b.jar:?]
	at chp.a(SourceFile:728) ~[18w19b.jar:?]
	at clm$4.a(SourceFile:223) ~[18w19b.jar:?]
	at ciq.mouseClicked(SourceFile:103) ~[18w19b.jar:?]
	at cjm.mouseClicked(SourceFile:45) ~[18w19b.jar:?]
	at clm.mouseClicked(SourceFile:507) ~[18w19b.jar:?]
	at chr.b(SourceFile:67) ~[18w19b.jar:?]
	at clh.a(SourceFile:429) ~[18w19b.jar:?]
	at chr.a(SourceFile:67) ~[18w19b.jar:?]
	at org.lwjgl.glfw.GLFWMouseButtonCallbackI.callback(GLFWMouseButtonCallbackI.java:23) [lwjgl-glfw-3.1.2.jar:?]
	at org.lwjgl.system.JNI.invokeV(Native Method) ~[lwjgl-3.1.2.jar:?]
	at org.lwjgl.glfw.GLFW.glfwWaitEventsTimeout(GLFW.java:2599) [lwjgl-glfw-3.1.2.jar:?]
	at chz.a(SourceFile:296) [18w19b.jar:?]
	at chp.c(SourceFile:845) [18w19b.jar:?]
	at chp.a(SourceFile:381) [18w19b.jar:?]
	at net.minecraft.client.main.Main.main(SourceFile:144) [18w19b.jar:?]

Created a few fresh worlds in 1.7.10 (default options), all spam this when opened on 18w19b.