Merge pull request CleverRaven#38020 from Fris0uman/exo_clean

Clean some exothermic CBM code

src/bionics.cpp

@@ -1096,12 +1096,14 @@ void Character::heat_emission( int b, int fuel_energy )
     }
     const float efficiency = bio.info().fuel_efficiency;
 
-    const int &heat_prod = fuel_energy * ( 1 - efficiency );
-    const int &heat_level = std::min( heat_prod / 10, 4 );
-    const int &heat_spread = std::max( heat_prod / 10 - heat_level, 1 );
+    const int heat_prod = fuel_energy * ( 1.0f - efficiency );
+    const int heat_level = std::min( heat_prod / 10, 4 );
     const emit_id hotness = emit_id( "emit_hot_air" + to_string( heat_level ) + "_cbm" );
-    g->m.emit_field( pos(), hotness, heat_spread );
-    for( const auto bp : bio.info().occupied_bodyparts ) {
+    if( hotness.is_valid() ) {
+        const int heat_spread = std::max( heat_prod / 10 - heat_level, 1 );
+        g->m.emit_field( pos(), hotness, heat_spread );
+    }
+    for( const std::pair<body_part, size_t> &bp : bio.info().occupied_bodyparts ) {
         add_effect( effect_heating_bionic, 2_seconds, bp.first, false, heat_prod );
     }
 }