Resolve "Safe and more complete print()"

Closes #363

src/factor/factor_base.cpp

@@ -315,17 +315,29 @@ void FactorBase::printHeader(int _depth, bool _constr_by, bool _metric, bool _st
         _stream << " Abs";
 
     for (const auto& Fow : getFrameOtherList())
-        if (!Fow.expired())
-            _stream << " Frm" << Fow.lock()->id();
+    {
+        auto Fow_sh = Fow.lock();
+        if (Fow_sh)
+            _stream << " Frm" << Fow_sh->id();
+    }
     for (const auto& Cow : getCaptureOtherList())
-        if (!Cow.expired())
-            _stream << " Cap" << Cow.lock()->id();
+    {
+        auto Cow_sh = Cow.lock();
+        if (Cow_sh)
+            _stream << " Cap" << Cow_sh->id();
+    }
     for (const auto& fow : getFeatureOtherList())
-        if (!fow.expired())
-            _stream << " Ftr" << fow.lock()->id();
+    {
+        auto fow_sh = fow.lock();
+        if (fow_sh)
+            _stream << " Ftr" << fow_sh->id();
+    }
     for (const auto& Low : getLandmarkOtherList())
-        if (!Low.expired())
-            _stream << " Lmk" << Low.lock()->id();
+    {
+        auto Low_sh = Low.lock();
+        if (Low_sh)
+            _stream << " Lmk" << Low_sh->id();
+    }
     _stream << std::endl;
 }