I managed to reproduce this error.
Casting the RHS to double in lines 430, 460 and 496 like this
x[i][j] = (double)(i + 1) * (j - 10);
fixes this issue for this test.
As to why this helps, I have less of an idea.
The same problem then arises in fwd/mat/fun/get_base1_lhs_test.cpp