Add pruning support (#12)

src/lib/Data.php

@@ -98,4 +98,14 @@ class Data {
             if (is_null($dbConn)) $db->close();
         }
     }
+
+    /**
+     * Return the last SQLite error message as a result array
+     *
+     * @param SQLite3 $db The database connection on which the error has occurred
+     * @return string[] ['error' => message] for last SQLite error message
+     */
+    public static function error(SQLite3 $db): array {
+        return ['error' => 'SQLite error: ' . $db->lastErrorMsg()];
+    }
 }