Fix admin verb to set unspawned ballisic ammo count (#26411)

Don't crash if an invalid value is given.

Content.Server/Administration/Systems/AdminVerbSystem.Tools.cs

@@ -718,9 +718,21 @@ public sealed partial class AdminVerbSystem
                 Icon = new SpriteSpecifier.Rsi(new("/Textures/Objects/Fun/caps.rsi"), "mag-6"),
                 Act = () =>
                 {
-                    _quickDialog.OpenDialog(player, "Set Bullet Amount", $"Amount (max {ballisticAmmo.Capacity}):", (int amount) =>
+                    _quickDialog.OpenDialog(player, "Set Bullet Amount", $"Amount (standard {ballisticAmmo.Capacity}):", (string amount) =>
                     {
-                        ballisticAmmo.UnspawnedCount = amount;
+                        if (!int.TryParse(amount, out var result))
+                            return;
+
+                        if (result > 0)
+                        {
+                            ballisticAmmo.UnspawnedCount = result;
+                        }
+                        else
+                        {
+                            ballisticAmmo.UnspawnedCount = 0;
+                        }
+
+                        _gun.UpdateBallisticAppearance(args.Target, ballisticAmmo);
                     });
                 },
                 Impact = LogImpact.Medium,