GOMA—A smoking trail of lava from a volcanic eruption covered hundreds of houses in eastern Congo on Sunday, leaving residents to pick gingerly through the wreckage, though the flow halted just short of the major city of Goma. Goma was thrown into panic on Saturday evening as Mount Nyiragongo erupted, turning the night sky an eerie red and sending a wall of orange lava downhill towards the lakeside city of about 2 million people. Thousands fled on foot with their belongings, some towards the nearby border with Rwanda. As the sun rose on Sunday a smoldering black gash could be seen on the outskirts of Goma, where the lava had cooled to rubble. At some points it was three stories high, engulfing even large buildings and sending smoke into the gray morning sky. Residents in the Buhene district sorted through the mangled white remains of tin roofs or lifted rocks— …