crashes on web page reload in firefox

[arekm]

When I go to http://sta.sh/muro/ then everything works fine but if I press F5 to reload page plugin crashes. firefox 37.0.2, linux, 64bit

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Reading symbols from /usr/lib64/iceweasel/plugin-container...Reading symbols from /usr/lib/debug/usr/lib64/iceweasel/plugin-container.debug...done.
done.

warning: core file may not match specified executable file.
[New LWP 13704]
[New LWP 13714]
[New LWP 13705]

warning: Could not load shared library symbols for linux-vdso.so.1.
Do you need "set solib-search-path" or "set sysroot"?
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib64/libthread_db.so.1".
Core was generated by `/usr/lib64/iceweasel/plugin-container /usr/lib64/browser-plugins/npWacomWebPlug'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0  Operate (aOp=PL_DHASH_LOOKUP, aKey=aKey@entry=0x7fed9f507dc0, this=0x0) at /usr/src/debug/iceweasel-37.0.2/mozilla/xpcom/glue/pldhash.cpp:561
561       PLDHashNumber keyHash = ops->hashKey(this, aKey);
(gdb) bt
#0  Operate (aOp=PL_DHASH_LOOKUP, aKey=aKey@entry=0x7fed9f507dc0, this=0x0) at /usr/src/debug/iceweasel-37.0.2/mozilla/xpcom/glue/pldhash.cpp:561
#1  PL_DHashTableLookup (aTable=0x0, aKey=aKey@entry=0x7fed9f507dc0) at /usr/src/debug/iceweasel-37.0.2/mozilla/xpcom/glue/pldhash.cpp:673
#2  0x00007fedb883e73e in nsTHashtable<mozilla::plugins::PluginScriptableObjectChild::NPObjectData>::GetEntry (this=<optimized out>, aKey=aKey@entry=0x7fed9f507dc0)
    at ../../../dist/include/nsTHashtable.h:132
#3  0x00007fedb8839368 in mozilla::plugins::PluginScriptableObjectChild::GetActorForNPObject (aObject=aObject@entry=0x7fed9f507dc0)
    at /usr/src/debug/iceweasel-37.0.2/mozilla/dom/plugins/ipc/PluginScriptableObjectChild.cpp:1222
#4  0x00007fedb882d435 in mozilla::plugins::PluginInstanceChild::GetActorForNPObject (this=this@entry=0x7fed9f50b210, aObject=0x7fed9f507dc0)
    at /usr/src/debug/iceweasel-37.0.2/mozilla/dom/plugins/ipc/PluginInstanceChild.cpp:2513
#5  0x00007fedb882d4cf in mozilla::plugins::PluginInstanceChild::AnswerNPP_GetValue_NPPVpluginScriptableNPObject (this=0x7fed9f50b210, aValue=0x7ffddfb03e10, 
    aResult=0x7ffddfb03de8) at /usr/src/debug/iceweasel-37.0.2/mozilla/dom/plugins/ipc/PluginInstanceChild.cpp:691
#6  0x00007fedb7f3b07f in mozilla::plugins::PPluginInstanceChild::OnCallReceived (this=0x7fed9f50b210, __msg=..., __reply=@0x7ffddfb03ff0: 0x0)
    at /usr/src/debug/iceweasel-37.0.2/mozilla/obj-x86_64/ipc/ipdl/PPluginInstanceChild.cpp:2106
#7  0x00007fedb7f3bdf3 in mozilla::plugins::PPluginModuleChild::OnCallReceived (this=this@entry=0x7feda8816830, __msg=..., __reply=@0x7ffddfb03ff0: 0x0)
    at /usr/src/debug/iceweasel-37.0.2/mozilla/obj-x86_64/ipc/ipdl/PPluginModuleChild.cpp:1036
#8  0x00007fedb7df958e in mozilla::ipc::MessageChannel::DispatchInterruptMessage (this=this@entry=0x7feda8816890, aMsg=..., stackDepth=stackDepth@entry=0)
    at /usr/src/debug/iceweasel-37.0.2/mozilla/ipc/glue/MessageChannel.cpp:1285
#9  0x00007fedb945c80c in mozilla::ipc::MessageChannel::DispatchMessage (this=this@entry=0x7feda8816890, aMsg=...)
    at /usr/src/debug/iceweasel-37.0.2/mozilla/ipc/glue/MessageChannel.cpp:1143
#10 0x00007fedb945c6de in mozilla::ipc::MessageChannel::OnMaybeDequeueOne (this=0x7feda8816890) at /usr/src/debug/iceweasel-37.0.2/mozilla/ipc/glue/MessageChannel.cpp:1129
#11 0x00007fedb9458e95 in MessageLoop::RunTask (this=0x7ffddfb05490, task=0x7feda88c09a0)
    at /usr/src/debug/iceweasel-37.0.2/mozilla/ipc/chromium/src/base/message_loop.cc:361
#12 0x00007fedb9458e6d in MessageLoop::DeferOrRunPendingTask (this=<optimized out>, pending_task=...)
    at /usr/src/debug/iceweasel-37.0.2/mozilla/ipc/chromium/src/base/message_loop.cc:369
#13 0x00007fedb907c4bc in MessageLoop::DoWork (this=0x7ffddfb05490) at /usr/src/debug/iceweasel-37.0.2/mozilla/ipc/chromium/src/base/message_loop.cc:447
#14 0x00007fedb7de05a5 in base::MessagePumpForUI::HandleDispatch (this=0x7feda8847460)
    at /usr/src/debug/iceweasel-37.0.2/mozilla/ipc/chromium/src/base/message_pump_glib.cc:261
#15 0x00007fedb7de05d8 in (anonymous namespace)::WorkSourceDispatch (source=<optimized out>, unused_func=<optimized out>, unused_data=<optimized out>)
    at /usr/src/debug/iceweasel-37.0.2/mozilla/ipc/chromium/src/base/message_pump_glib.cc:106
#16 0x00007fedaf99e06b in g_main_context_dispatch () from /usr/lib64/libglib-2.0.so.0
#17 0x00007fedaf99e3d8 in ?? () from /usr/lib64/libglib-2.0.so.0
#18 0x00007fedaf99e47c in g_main_context_iteration () from /usr/lib64/libglib-2.0.so.0
#19 0x00007fedb7de0161 in base::MessagePumpForUI::RunWithDispatcher (this=0x7feda8847460, delegate=<optimized out>, dispatcher=<optimized out>)
    at /usr/src/debug/iceweasel-37.0.2/mozilla/ipc/chromium/src/base/message_pump_glib.cc:192
#20 0x00007fedb9458989 in RunHandler (this=0x7ffddfb05490) at /usr/src/debug/iceweasel-37.0.2/mozilla/ipc/chromium/src/base/message_loop.cc:226
#21 MessageLoop::Run (this=this@entry=0x7ffddfb05490) at /usr/src/debug/iceweasel-37.0.2/mozilla/ipc/chromium/src/base/message_loop.cc:200
#22 0x00007fedb8cd25a4 in XRE_InitChildProcess (aArgc=<optimized out>, aArgv=<optimized out>, aGMPLoader=<optimized out>)
    at /usr/src/debug/iceweasel-37.0.2/mozilla/toolkit/xre/nsEmbedFunctions.cpp:575
#23 0x000000000040b053 in content_process_main (argc=10, argv=0x7ffddfb05778) at /usr/src/debug/iceweasel-37.0.2/mozilla/ipc/contentproc/plugin-container.cpp:211
---Type <return> to continue, or q <return> to quit---
#24 0x00007fedb5dc4860 in __libc_start_main () from /lib64/libc.so.6
#25 0x000000000040ad49 in _start () at ../sysdeps/x86_64/start.S:118
(gdb) frame 1
#1  PL_DHashTableLookup (aTable=0x0, aKey=aKey@entry=0x7fed9f507dc0) at /usr/src/debug/iceweasel-37.0.2/mozilla/xpcom/glue/pldhash.cpp:673
673       return aTable->Operate(aKey, PL_DHASH_LOOKUP);
(gdb) print aKey
$1 = (const void *) 0x7fed9f507dc0
(gdb) print *aKey
Attempt to dereference a generic pointer.
(gdb) print aTable
$2 = (PLDHashTable *) 0x0
(gdb) l
668     }
669
670     PLDHashEntryHdr* PL_DHASH_FASTCALL
671     PL_DHashTableLookup(PLDHashTable* aTable, const void* aKey)
672     {
673       return aTable->Operate(aKey, PL_DHASH_LOOKUP);
674     }
675
676     PLDHashEntryHdr* PL_DHASH_FASTCALL
677     PL_DHashTableAdd(PLDHashTable* aTable, const void* aKey)
(gdb)