Rendering error without any plausible reason

[enzotib]

The following text produce, on Save & Get URL, the following error message

ERROR: Improper code!

The text of the markdown is the following

### Review of
# Heat flow influence on the Cauchy stress tensor in a thermal wave
### by A.Y. Beliaev, L.A. Komar and A.L. Svistkov

In this manuscript the authors investigate, by mean of Rational Thermoelasticity, the possibility that internal energy density or entropy density depends on heat flux, but not both. For the heat flux is considered a costant relaxing time depending on the material. Moreover, the dependence of the Cauchy stress tensor on heat flux is considered.

1. First of all, I suppose that with the expression "mass density of the internal energy" the authors intend "density of the internal energy per unit mass". I suggest to use this second form that in my opinion is more correct. The same can be applied to the expression "mass density of the entropy".
2. this is the second point

[enzotib]

I eventullay solved the issue by inserting a ${}$ token in a random place.
It seems that the app expects at least a mathematical object, otherwise shows that error.

[susam]

I am glad you were able to resolve the issue. The live deployment of this application at https://mathb.in/ does expect some mathematics delimiter to be present. MathB.in is intended to be a mathematics snippet sharing service. It is not meant for general text.