Unreachable not defined should be a better error

[willow-ahrens]

julia> eval(@finch_kernel function ssyrk(C, A)
                  for l = _, j = _
                      temp1 = A[j, l]
                      for i = _
                          temp3 = A[i, l]
                          if uptrimask[i+1, j]
                              temp2 = temp1 * temp3
                              C[i, j] += temp2
                              # C[j, i] += temp2
                          end
                          if i == j
                              C[i, j] += temp1 * temp3
                          end
                      end
                  end
               for j = _, i = _
                  w[j, i] = C[i, j]
               end
           end
        )
ssyrk (generic function with 1 method)