Cant get diagram.lua to work with tikz

Hi, im sorry but i have to ask if i miss something obvious. What i have done on a fresh ubuntu system:

installed pandoc and verfied that it works
install texlive-latex-base and verify that pdflatex works from the command line
install inkscape and verify that the inkscape command works from the command line (for me it opens the program)
downloaded the file diagram.lua and put it in my home directory along with the following input.tex:

My input.tex
```
Some math $x^2$.
Here is a circle:
\begin{tikzpicture}
\draw (0,0) circle (1in);
\end{tikzpicture}
```

Some more math $\mathbb{R}$.


Now i call pandoc like this

pandoc input.tex -o output.html -f latex -t html --embed-resources --lua-filter=diagram.lua

**Expected outcome:**
An output.html file containg an svg div.

**Actual outcome:**
output.html
```html
<p>Some math <span class="math inline"><em>x</em><sup>2</sup></span>.
Here is a circle:</p>
<p>Some more math <span class="math inline">ℝ</span>.</p>

There is no image clue to be seen. Also the conversion is extremely fast, which makes me doubt that inkscape has been used. (if i start inkscape as a gui it takes a few seconds). I get no errors or warnings that i can see. Also i get the exact same output file if i leave the filter out completely:

pandoc input.tex -o output.html -f latex -t html --embed-resources

Is there something i have to install to use this package?

pandoc-ext / diagram

Cant get diagram.lua to work with tikz #46