Jason Molina’s work through Magnolia Electric Co. and Songs: Ohia made him the Townes Van Zandt of his generation, an under-the-radar, grizzled songwriter saturated in sadness with a mind for direct, folksy poetry. On Sunday, Molina biographer Erin Osman reads from her book “Jason Molina: Riding with the Ghost” at Guestroom Records. Guest DJs will be spinning Molina’s music starting at 1 p.m., and at 2 p.m. Osman will read from her book.