Prevented negative temporary hitpoints being added

rpg-docs/client/views/character/stats/addTHPDialog/addTHPDialog.js

@@ -1,9 +1,11 @@
 Template.addTHPDialog.events({
 	"tap #addButton": function(event, instance){
+		var max = +instance.find("#quantityInput").value;
+		if (!max || max < 0) max = 0;
 		TemporaryHitPoints.insert({
 			charId: this.charId,
 			name: instance.find("#nameInput").value,
-			maximum: +instance.find("#quantityInput").value,
+			maximum: max,
 			deleteOnZero: !!instance.find("#deleteWhenZeroCheckbox").checked,
 		});
 	}