fix bug in field_have_same_type

src/field.h

@@ -295,8 +295,8 @@ inline bool field_have_same_type(const Field_t& field1, const Field_t& field2) {
   if(std::holds_alternative<FieldFloat>(field1) &&
      std::holds_alternative<FieldFloat>(field2)) {
     return true;
-  } else if(std::holds_alternative<FieldFloat>(field1) &&
-            std::holds_alternative<FieldFloat>(field2)) {
+  } else if(std::holds_alternative<FieldDouble>(field1) &&
+            std::holds_alternative<FieldDouble>(field2)) {
     return true;
   } else {
     return false;