Do not show duration for infinite light sources as -1

apps/openmw/mwclass/light.cpp

@@ -161,7 +161,12 @@ namespace MWClass
         std::string text;
 
         if (Settings::Manager::getBool("show effect duration","Game"))
-            text += "\n#{sDuration}: " + MWGui::ToolTips::toString(ptr.getClass().getRemainingUsageTime(ptr));
+        {
+            // -1 is infinite light source, so duration makes no sense here. Other negative values are treated as 0.
+            float remainingTime = ptr.getClass().getRemainingUsageTime(ptr);
+            if (remainingTime != -1.0f)
+                text += "\n#{sDuration}: " + MWGui::ToolTips::toString(std::max(0.f, remainingTime));
+        }
 
         text += MWGui::ToolTips::getWeightString(ref->mBase->mData.mWeight, "#{sWeight}");
         text += MWGui::ToolTips::getValueString(ref->mBase->mData.mValue, "#{sValue}");