The errors will be better in 6.0.6, but the crux of the problem is the second call to blur:
"first = blur(input, in2);
second = blur(first, in3);"
The first argument to blur has to be a direct input in1, in2, ... at the patcher level because it's being used as the first argument to a sample function. The first argument to sample always has to be an input from [in 1], etc. It's not possible to combine these two separate gl.pix objects together and get the same effect. That's just the way separable convolution works.