Add distinction between different data types when checking 'sense'

pypsa/optimization/abstract.py

@@ -381,13 +381,20 @@ def optimize_mga(
         objective + fixed_cost <= (1 + slack) * optimal_cost, name="budget"
     )
 
-    # parse optimization sense
-    if sense.startswith("min") or sense > 0:
-        sense = 1
-    elif sense.startswith("max") or sense < 0:
-        sense = -1
+    if isinstance(sense, str):
+        if sense.startswith("min"):
+            sense = 1
+        elif sense.startswith("max"):
+            sense = -1
+        else:
+            raise ValueError(f"Could not parse optimization sense {sense}")
     else:
-        raise ValueError(f"Could not parse optimization sense {sense}")
+        if sense > 0:
+            sense = 1
+        elif sense < 0:
+            sense = -1
+        else:
+            raise ValueError(f"Could not parse optimization sense {sense}")
 
     # build alternate objective
     objective = []