A detailed walkthrough of the error, its code path and all known details is as follows:
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-- Head --
Stacktrace:
    at avf.ar(SourceFile:560)
    at avf.am(SourceFile:361)

-- Initialization --
Details:
Stacktrace:
    at avf.a(SourceFile:310)
    at net.minecraft.client.main.Main.main(SourceFile:124)

-- System Details --
Details:
    Minecraft Version: 1.8.3
    Operating System: Linux (amd64) version 3.13.0-46-generic
    CPU: 4x Intel(R) Atom(TM) CPU D525 @ 1.80GHz
    Java Version: 1.7.0_75, Oracle Corporation
    Java VM Version: OpenJDK 64-Bit Server VM (mixed mode), Oracle Corporation
    Memory: 72935880 bytes (69 MB) / 164499456 bytes (156 MB) up to 1060372480 bytes (1011 MB)
    JVM Flags: 5 total; -Xmx1G -XX:+UseConcMarkSweepGC -XX:+CMSIncrementalMode -XX:-UseAdaptiveSizePolicy -Xmn128M
    IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
    Launched Version: 1.8.3
    LWJGL: 2.9.4
    OpenGL: ~~ERROR~~ RuntimeException: No OpenGL context found in the current thread.
    GL Caps:
    Using VBOs: No
    Is Modded: Probably not. Jar signature remains and client brand is untouched.
    Type: Client (map_client.txt)
    Resource Packs: []
    Current Language: ~~ERROR~~ NullPointerException: null
    Profiler Position: N/A (disabled)