Crash on Loading/Creating Single Player Worlds

Minecraft Crash Report ----
// I let you down. Sorry 😞

Time: 5/3/16 8:19 PM
Description: Updating screen events

java.lang.StringIndexOutOfBoundsException: String index out of range: -1
at java.lang.String.charAt(String.java:658)
at io.netty.bootstrap.Bootstrap.isBlockedServer(Bootstrap.java:279)
at io.netty.bootstrap.Bootstrap.checkAddress(Bootstrap.java:268)
at io.netty.bootstrap.Bootstrap.doConnect(Bootstrap.java:149)
at io.netty.bootstrap.Bootstrap.connect(Bootstrap.java:131)
at em.a(SourceFile:306)
at bcd.a(SourceFile:2143)
at bhl.e(SourceFile:227)
at bhl.a(SourceFile:182)
at bhl.a(SourceFile:148)
at bdj.b(SourceFile:41)
at bhk.a(SourceFile:118)
at bez.k(SourceFile:404)
at bhk.k(SourceFile:50)
at bez.p(SourceFile:381)
at bcd.t(SourceFile:1582)
at bcd.av(SourceFile:969)
at bcd.a(SourceFile:399)
at net.minecraft.client.main.Main.main(SourceFile:124)

A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------

– Head –
Thread: Client thread
Stacktrace:
at java.lang.String.charAt(String.java:658)
at io.netty.bootstrap.Bootstrap.isBlockedServer(Bootstrap.java:279)
at io.netty.bootstrap.Bootstrap.checkAddress(Bootstrap.java:268)
at io.netty.bootstrap.Bootstrap.doConnect(Bootstrap.java:149)
at io.netty.bootstrap.Bootstrap.connect(Bootstrap.java:131)
at em.a(SourceFile:306)
at bcd.a(SourceFile:2143)
at bhl.e(SourceFile:227)
at bhl.a(SourceFile:182)
at bhl.a(SourceFile:148)
at bdj.b(SourceFile:41)
at bhk.a(SourceFile:118)
at bez.k(SourceFile:404)
at bhk.k(SourceFile:50)
at bez.p(SourceFile:381)

– Affected screen –
Details:
Screen name: bex
Stacktrace:
at bcd.t(SourceFile:1582)
at bcd.av(SourceFile:969)
at bcd.a(SourceFile:399)
at net.minecraft.client.main.Main.main(SourceFile:124)

– System Details –
Details:
Minecraft Version: 1.9.3-pre3
Operating System: Mac OS X (x86_64) version 10.11.4
Java Version: 1.8.0_74, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 63289600 bytes (60 MB) / 261844992 bytes (249 MB) up to 2134114304 bytes (2035 MB)
JVM Flags: 5 total; -Xmx2G -XX:+UseConcMarkSweepGC -XX:+CMSIncrementalMode -XX:-UseAdaptiveSizePolicy -Xmn128M
IntCache: cache: 0, tcache: 0, allocated: 12, tallocated: 94
Launched Version: 1.9.3-pre3
LWJGL: 2.9.2
OpenGL: NVIDIA GeForce GT 650M OpenGL Engine GL version 2.1 NVIDIA-10.10.5.2 310.42.25f01, NVIDIA Corporation
GL Caps: Using GL 1.3 multitexturing.
Using GL 1.3 texture combiners.
Using framebuffer objects because ARB_framebuffer_object is supported and separate blending is supported.
Shaders are available because OpenGL 2.1 is supported.
VBOs are available because OpenGL 1.5 is supported.

Using VBOs: Yes
Is Modded: Probably not. Jar signature remains and client brand is untouched.
Type: Client (map_client.txt)
Resource Packs:
Current Language: English (US)
Profiler Position: N/A (disabled)
CPU: bcd$7@4e782401

This crash only affects single player worlds in 1.7.x and higher up to 1.9.3 pre release versions. Earlier versions and multiplayer servers are unaffected. 1.9 vanilla works fine on third party launchers but for some reason crashes when using the official launcher.This started happing after updating OS X from 10.11.3 to 10.11.4