See attached screenshot for the reproducible situation. Despite having safe places at the head and foot of the bed, the player will consistently awaken in the 1-block deep lava, dying as a result and losing all their goodies. Orientation n-s or e-w makes no difference.

This is reproducible by simply recreating the situation as pictured...
1-block wide safe passage over 1-block-deep lava, with the walls being at y=_{1 but air at y=}.