PVS-Studio warning V547 for ReactOS

typedef unsigned int GLuint;

const GLubyte *_mesa_get_enabled_extension(
  struct gl_context *ctx, GLuint index)
{
  const GLboolean *base;
  size_t n;
  const struct extension *i;
  if (index < 0)
    return NULL;
  ....
}

This suspicious code was found in ReactOS project by PVS-Studio static code analyzer.
Warning message is:
V547 Expression 'index < 0' is always false. Unsigned type value is never < 0. extensions.c 936

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