fix: exit with error on shader compilation failure

src/gfx.cpp

@@ -46,6 +46,7 @@ GLuint compileShaderProgram()
         glGetProgramInfoLog(shaderProgram, 512, NULL, infoLog);
         std::cerr << "shader linking failed" << std::endl
             << infoLog << std::endl;
+        exit(-1);
     }
 
     // We no longer need the individual shaders