You are almost there...
From the interactive gdb session you can now inspect the frames that look suspicious. In this case my first guess was to look at 'setFromTriplets'' (frame 5).
I then printed the 'triplets' object:
(gdb) p triplets
$2 = std::vector of length 724, capacity 724 = {{m_row = 0, m_col = 0, m_value = 1}, {m_row = 0, m_col = 0, m_value = 1}, {m_row = 0, m_col = 0,
m_value = 1}, {m_row = 0, m_col = 207145260, m_value = 4.6344408982361827e-310}, {m_row = 1, m_col = 1, m_value = 1}, {m_row = 1, m_col = 1,
m_value = 1}, {m_row = 1, m_col = 1, m_value = 1}, {m_row = 2, m_col = 2, m_value = 1}, {m_row = 2, m_col = 2, m_value = 1}, {m_row = 2,
m_col = 2, m_value = 1}, {m_row = 2, m_col = 21840, m_value = 0}, {m_row = 3, m_col = 3, m_value = 1}, {m_row = 3, m_col = 3, m_value = 1}
There's definitely something wrong with this element:
m_row = 0, m_col = 207145260, m_value = 4.6344408982361827e-310}
Hopefully that gives you a clue on what to fix.