[FIX] xlsx: ignore charts without data set

When we parse the XML and extract the data sets, we expect an element
`c:val`. But this element is optional according to the spec.

It leads to a chart with a `dataSets` property being an empty array.
It crashes (17.0) or the chart is ignored (18.0) later down the line
because a chart without any data set makes no sense.

I must admit I do not fully understand what are those charts without
data set in excel. When importing the file in Excel Online or Google
Sheet, there's no chart...

With this commit, we ignore those charts as well.

closes #5427

Opw: 4443811
Task: 4460515
X-original-commit: fedb344
Signed-off-by: Rémi Rahir (rar) <[email protected]>
Signed-off-by: Lucas Lefèvre (lul) <[email protected]>

src/xlsx/conversion/figure_conversion.ts

@@ -63,7 +63,7 @@ function convertFigure(
 }
 
 function isChartData(data: ExcelChartDefinition | ExcelImage): data is ExcelChartDefinition {
-  return "dataSets" in data;
+  return "dataSets" in data && data.dataSets.length > 0;
 }
 
 function isImageData(data: ExcelChartDefinition | ExcelImage): data is ExcelImage {