Fix non-battery fueled items using charges

Only test the energy remaining if the item uses energy, otherwise test
the ammo, as before.

Adds a regression test too.

src/item.cpp

@@ -10858,8 +10858,25 @@ int item::ammo_remaining( const bool include_linked ) const
     return ammo_remaining( nullptr, include_linked );
 }
 
+bool item::uses_energy() const
+{
+    if( is_vehicle_battery() ) {
+        return true;
+    }
+    const item *mag = magazine_current();
+    if( mag && mag->uses_energy() ) {
+        return true;
+    }
+    return has_flag( flag_USES_BIONIC_POWER ) ||
+           has_flag( flag_USE_UPS ) ||
+           ( is_magazine() && ammo_capacity( ammo_battery ) > 0 );
+}
+
 units::energy item::energy_remaining( const Character *carrier ) const
 {
+    if( !uses_energy() ) {
+        return 0_kJ;
+    }
     units::energy ret = 0_kJ;
 
     // Future energy based batteries
@@ -14103,8 +14120,9 @@ bool item::process_tool( Character *carrier, const tripoint &pos )
     }
 
     // if insufficient available charges shutdown the tool
-    if( ( type->tool->turns_per_charge > 0 || type->tool->power_draw > 0_W ) &&
-        energy_remaining( carrier ) < energy_per_second() ) {
+    if( ( type->tool->power_draw > 0_W || type->tool->turns_per_charge > 0 ) &&
+        ( ( uses_energy() && energy_remaining( carrier ) < energy_per_second() ) ||
+          ( !uses_energy() && ammo_remaining( carrier, true ) == 0 ) ) ) {
         if( carrier && has_flag( flag_USE_UPS ) ) {
             carrier->add_msg_if_player( m_info, _( "You need an UPS to run the %s!" ), tname() );
         }

src/item.h

@@ -2442,6 +2442,8 @@ class item : public visitable
          */
         int shots_remaining( const Character *carrier ) const;
 
+        // Does this use electrical energy, or is it fueled by something else?
+        bool uses_energy() const;
         /**
          * Energy available from battery/UPS/bionics
          * @param carrier is used for UPS and bionic power.

tests/active_item_test.cpp

@@ -44,6 +44,34 @@ TEST_CASE( "active_items_processed_regularly", "[active_item]" )
     CHECK( here.i_at( player_character.pos_bub() ).only_item().typeId().str() == "chainsaw_off" );
 }
 
+TEST_CASE( "non_energy_tool_power_consumption_rate", "[active_item]" )
+{
+    // Gasoline lantern without a battery, using gasoline instead
+    item test_lantern( "gasoline_lantern_on" );
+    const itype_id &default_ammo = test_lantern.ammo_default();
+    const int ammo_capacity = test_lantern.ammo_capacity( default_ammo->ammo->type );
+    test_lantern.ammo_set( default_ammo, ammo_capacity );
+    REQUIRE_FALSE( test_lantern.uses_energy() );
+
+    test_lantern.active = true;
+
+    // Now process the tool until it runs out of fuel.
+    int seconds_active = 0;
+    map &here = get_map();
+    // Must be captured before it's inactive and transforms
+    int turns_per_charge = test_lantern.type->tool->turns_per_charge;
+    REQUIRE( test_lantern.ammo_remaining() == ammo_capacity );
+    do {
+        calendar::turn += 1_seconds;
+        test_lantern.process( here, nullptr, tripoint_zero );
+        seconds_active++;
+    } while( test_lantern.active );
+    REQUIRE( test_lantern.ammo_remaining() == 0 );
+    // Runtime vaguely in the bounds we expect.
+    CHECK( seconds_active > ( turns_per_charge - 1 ) * ammo_capacity );
+    CHECK( seconds_active < ( turns_per_charge + 1 ) * ammo_capacity );
+}
+
 TEST_CASE( "tool_power_consumption_rate", "[active_item]" )
 {
     // Give the flashlight a fully charged battery, 56 kJ