You are trying to index into a scalar (non-iterable) value:
[y[1] for y in y_test]
# ^ this is the problem
When you call [y for y in test] you are iterating over the values already, so you get a single value in y.
Your code is the same as trying to do the following:
y_test = [1, 2, 3]
y = y_test[0] # y = 1
print(y[0]) # this line will fail
I'm not sure what you're trying to get into your results array, but you need to get rid of [y[1] for y in y_test].
If you want to append each y in y_test to results, you'll need to expand your list comprehension out further to something like this:
[results.append(..., y) for y in y_test]
Or just use a for loop:
for y in y_test:
results.append(..., y)