fix: fix input_gas_network conditions when no carriers

Author: tgilon

rules/build_sector.smk

@@ -1658,10 +1658,12 @@ def input_gas_network(w):
     if gas_network or h2_retrofit:
         inputs["clustered_gas_network"] = resources("gas_network_base_s_{clusters}.csv")
 
-    gas_imports = "gas" in import_carriers
-    h2_imports_not_tyndp = "H2" in import_carriers and not h2_topology_tyndp
+    gas_imports = imports_enabled and "gas" in import_carriers
+    h2_imports_not_tyndp = (
+        imports_enabled and "H2" in import_carriers and not h2_topology_tyndp
+    )
 
-    if gas_network or (imports_enabled and (gas_imports or h2_imports_not_tyndp)):
+    if gas_network or gas_imports or h2_imports_not_tyndp:
         inputs["gas_input_nodes_simplified"] = resources(
             "gas_input_locations_s_{clusters}_simplified.csv"
         )