(cl-glut-examples:run-examples) raises error

[Valera]

Hi! When I launch (cl-glut-examples:run-examples) I get an error in shader-vao example. If I launch (cl-glut-examples:shader-vao) separately, even without restarting sbcl, it works correctly.

SBCL 2.1.6, all quicklisp dists are of version 20210807 (latest).

Trace:

OpenGL signalled (1281 . INVALID-VALUE) from GET-UNIFORM-LOCATION.
   [Condition of type CL-OPENGL-BINDINGS:OPENGL-ERROR]

Backtrace:
 0: (CL-OPENGL-BINDINGS:CHECK-ERROR #<unavailable argument>)
 1: (CL-OPENGL-BINDINGS:GET-UNIFORM-LOCATION 3 #.(SB-SYS:INT-SAP #X7FB05E159030))
 2: (CL-OPENGL:GET-UNIFORM-LOCATION 3 "angle")
 3: ((:METHOD CL-GLUT:TICK (CL-GLUT-EXAMPLES::SHADER-VAO-WINDOW)) #<CL-GLUT-EXAMPLES::SHADER-VAO-WINDOW {1004A679D3}>) [fast-method]
 4: ((LAMBDA (CL-GLUT::TICK-ID) :IN "/home/x/quicklisp/dists/quicklisp/software/cl-opengl-20191130-git/glut/interface.lisp") 2)
 5: ((LAMBDA (SB-ALIEN::ARGS-POINTER SB-ALIEN::RESULT-POINTER FUNCTION) :IN "/home/x/quicklisp/dists/quicklisp/software/cl-opengl-20191130-git/glut/interface.lisp") #<unavailable argument> #<unavai..
 6: ("foreign function: funcall_alien_callback")
 7: ("foreign function: callback_wrapper_trampoline")
 8: ("foreign function: #x50100C02")
 9: (CL-GLUT:MAIN-LOOP)
10: (CL-GLUT-EXAMPLES:RUN-EXAMPLES)

[3b]

Found some problems with the way run-examples was doing things (#111), and tried to work around that, so hopefully fixed now.