check for nullptr in HybridConditional::equals

gtsam/hybrid/HybridConditional.cpp

@@ -117,6 +117,22 @@ bool HybridConditional::equals(const HybridFactor &other, double tol) const {
     return other != nullptr && dc->equals(*other, tol);
   }
   return inner_->equals(*(e->inner_), tol);
+
+  if (inner_) {
+    if (e->inner_) {
+      // Both the inner_ factors are not null
+      return inner_->equals(*(e->inner_), tol);
+    } else {
+      return false;
+    }
+  } else {
+    if (e->inner_) {
+      return false;
+    } else {
+      // Both inner_ are null
+      return true;
+    }
+  }
 }
 
 /* ************************************************************************ */