0.9.0 ofTexture retain method causes exception: "map/set iterators incompatible"

0.9.0 ofTexture retain method causes exception: "map/set iterators incompatible". This was found on Visual Studio 2015 hosted on Windows 8.1:

Original code:

static void retain(GLuint id){
if(id!=0){
if(getTexturesIndex().find(id)!=getTexturesIndex().end()){
getTexturesIndex()[id]++;
}else{
getTexturesIndex()[id]=1;
}
}
}

Patched code:

void retain(GLuint id){
if(id!=0){

	if((!getTexturesIndex().empty())&&(getTexturesIndex().find(id) != getTexturesIndex().end())){
		getTexturesIndex()[id]++;
	}else{
		getTexturesIndex()[id]=1;
	}
}

}