Stop NPCs throwing guns, fix throwing logic

When CleverRaven#49907 was cleaning up NPC attack logic, it introduced a check into
many of the npc_attack_*::use functions to ensure that the NPC was
wielding the weapon of choice, and if they were not wielding it, ensure
that they did so they could perform that attack next.

However, for the throwing attack, it checked if the wielded item was
being wielded, causing this section to never be entered, and so the NPC
would throw whatever their wielded item was, or, if they were not
wielding an item, fail to perform an attack.

In addition to this, add a check to ensure we can wield the appropriate
item to npc_attack_throw::can_use.

Also, make sure all NPC actions have a name to ease debugging.

src/npc_attack.cpp

@@ -570,8 +570,8 @@ std::vector<npc_attack_rating> npc_attack_activate_item::all_evaluations( const
 
 void npc_attack_throw::use( npc &source, const tripoint &location ) const
 {
-    if( !source.is_wielding( source.get_wielded_item() ) ) {
-        if( !source.wield( source.get_wielded_item() ) ) {
+    if( !source.is_wielding( thrown_item ) ) {
+        if( !source.wield( thrown_item ) ) {
             debugmsg( "ERROR: npc tried to equip a weapon it couldn't wield" );
         }
         return;
@@ -608,6 +608,10 @@ bool npc_attack_throw::can_use( const npc &source ) const
         return false;
     }
 
+    if( !source.is_wielding( thrown_item ) && !source.can_wield( thrown_item ).success() ) {
+        return false;
+    }
+
     item single_item( thrown_item );
     if( single_item.count_by_charges() ) {
         single_item.charges = 1;

src/npcmove.cpp

@@ -4385,7 +4385,11 @@ std::string npc_action_name( npc_action action )
             return "Escape explosion";
         case npc_player_activity:
             return "Performing activity";
-        default:
+        case npc_noop:
+            return "Do nothing";
+        case npc_do_attack:
+            return "Attack";
+        case num_npc_actions:
             return "Unnamed action";
     }
 }