handle missing dual values when barrier solution has no crossover

Author: danielelerede-oet

linopy/solvers.py

@@ -1405,14 +1405,16 @@ def get_solver_solution() -> Solution:
                 m.solution.get_values(), m.variables.get_names(), dtype=float
             )
 
-            if is_lp:
+            try:
                 dual = pd.Series(
                     m.solution.get_dual_values(),
                     m.linear_constraints.get_names(),
                     dtype=float,
                 )
-            else:
-                logger.warning("Dual values of MILP couldn't be parsed")
+            except Exception:
+                logger.warning(
+                    "Dual values not available (e.g. barrier solution without crossover)"
+                )
                 dual = pd.Series(dtype=float)
             return Solution(solution, dual, objective)