[Fluxus] shader example crash

[gabor papp]

i'm not sure if fluxus compiled with GLSL=1 is supposed to be running on
machines without shader support, but i was running (self-test) and it
crashes on the shader example.

backtrace is attached:
(gdb) backtrace
#0  0x00000000 in ?? ()
#1  0x026977fd in Fluxus::GLSLShader::GLSLShader (this=0xaf5c40,
pair=@0xa35c50) at libfluxus/src/GLSLShader.cpp:153
#2  0x0269896f in Fluxus::ShaderCache::Get (vert=@0xbfffe8b8,
frag=@0xbfffe8c4) at libfluxus/src/ShaderCache.cpp:41
#3  0x0263dbdc in shader (argc=4204116, argv=0x9e4fa8) at
modules/fluxus-engine/src/LocalStateFunctions.cpp:2081
#4  0x005fc12e in scheme_do_eval ()
#5  0x005fbdb8 in scheme_do_eval ()
#6  0x005fba4d in scheme_do_eval ()
#7  0x0070906c in define_execute_with_dynamic_state ()
#8  0x007095e6 in define_values_execute ()
#9  0x005fb37e in scheme_do_eval ()
#10 0x00600546 in eval_k ()
#11 0x00615d3c in scheme_top_level_do_worker ()
#12 0x00615ef1 in scheme_top_level_do ()
#13 0x00600a02 in scheme_eval_compiled_multi ()
#14 0x00600a54 in scheme_eval_multi ()
#15 0x00600be4 in do_eval_string_all ()
#16 0x000085f9 in fluxus::Interpreter::Interpret (str=@0x402654, ret=0x0,
abort=false) at src/Interpreter.cpp:163
#17 0x000116ab in DisplayCallback () at src/main.cpp:162
#18 0x3e0059d1 in -[GLUTView drawRect:] ()
#19 0x3e009349 in -[GLUTView handleWorkEvent:] ()
#20 0x3e023869 in processWindowWorkList ()
#21 0x3e0238d1 in __glutProcessWorkEvents ()
#22 0x3e011a56 in -[GLUTApplication run] ()
#23 0x3e023307 in glutMainLoop ()
#24 0x00011f53 in run (se=0xd2a258, argc=1, argv=0xbffff7f8) at
src/main.cpp:341
#25 0x005c8846 in call_with_basic ()
#26 0x005c88a2 in scheme_main_stack_setup ()
#27 0x005c890c in scheme_main_setup ()
#28 0x0000fdb1 in main (argc=4204116, argv=0x402654) at src/main.cpp:348

if compiled with GLSL=0, fluxus does not crash.

best,
gabor