How can i solved the bug caused by postprocessor:AddTextureSampler()?

[infiniteob]

I used the function in this way:

local texpath = "images/noise_texture.tex"

table.insert(Assets,Asset("IMAGE", texpath))

AddModShadersInit(function()

/...code.../

    local PostProcessor = GLOBAL.PostProcessor

    TexSamplers.noise_tex=PostProcessor:AddTextureSampler(texpath)--when this code is annotated the game can start properly

/....code..../

end)

then the game crashed when i load a save

and the log says 

"Assert failure 'mTex != INVALID_RESOURCE_HANDLE' at ..\source\game\render\PostProcessor.cpp(459): Trace follows..."

What's the proper form for  the parameter accepted by the function postprocessor:AddTextureSampler() or is there something else wrong?

remarks:

I have tried something like "resolvefilepath" or "softresolvefilepath" or just using the absolute path but none of them works.