Fix segfault errors in getTarget and hasTarget on Linux

src/IDABot.cpp

@@ -383,4 +383,4 @@ float IDABot::UpgradeResearchTime(sc2::UpgradeID upgrade_id) const
 float IDABot::RadiusEffect(sc2::EffectID effect_id) const
 {
 	return Observation()->GetEffectData()[effect_id].radius;
-}
\ No newline at end of file
+}

src/Unit.cpp

@@ -337,16 +337,27 @@ Unit Unit::getTarget() const
     BOT_ASSERT(isValid(), "Unit is not valid");
     // if unit has order, check tag of target of first order
     if(getUnitPtr()->orders.size() > 0){
-		// t_id is set to the unit tag of the target
-		CCUnitID t_id = getUnitPtr()->orders[0].target_unit_tag;
-
-		// if it doesn't have a target. Return itself
-		if (m_bot->GetUnit(t_id) == nullptr) {
-			return *this;
-		}
+        // t_id is set to the unit tag of the target
+	CCUnitID t_id = getUnitPtr()->orders[0].target_unit_tag;
+	
+	// Make sure the returned tag is not the NullTag
+	if (t_id == sc2::NullTag) {
+	    return *this;
+	}
+	
+	// Make sure the Tag references a valid unit
+	if (m_bot->Observation()->GetUnit(t_id) == nullptr) {
+	    return *this; 
+	}
 
-		// IDABot finds the unit with this tag
-		return m_bot->GetUnit(t_id);
+	// Convert the tag to a Unit object
+	Unit unit = m_bot->GetUnit(t_id);
+	
+	if (unit.isValid()) {
+	    return unit;
+	} else {
+	    return *this;
+	}
     }
     return *this;
 }
@@ -356,10 +367,16 @@ bool Unit::hasTarget() const
     BOT_ASSERT(isValid(), "Unit is not valid");
 
     if (getUnitPtr()->orders.size() > 0) {
-        if (getUnitPtr()->orders[0].target_unit_tag != NULL) {
+        if (getUnitPtr()->orders[0].target_unit_tag != sc2::NullTag) {
             CCUnitID t_id = getUnitPtr()->orders[0].target_unit_tag;
-            // IDABot finds the unit with this tag, and returns true if valid
-            return m_bot->GetUnit(t_id).isValid();
+
+	    if (m_bot->Observation()->GetUnit(t_id) == nullptr) {
+		return false;
+	    }
+
+	    Unit unit = m_bot->GetUnit(t_id);
+
+            return unit.isValid();
         }
     }
 
@@ -504,4 +521,4 @@ float Unit::maxShields() const
 float Unit::maxEnergy() const
 {
 	return m_unit->energy_max;
-}
\ No newline at end of file
+}