Error message when font doesn't support math

library/src/math/mod.rs

@@ -198,6 +198,9 @@ impl Layout for FormulaNode {
                 Some(font)
             })
         else {
+            if let Some(span) = self.body.span() {
+                bail!(span, "current font does not support math");
+            }
             return Ok(Fragment::frame(Frame::new(Size::zero())))
         };
 

src/model/eval.rs

@@ -553,7 +553,8 @@ impl Eval for ast::Math {
             self.exprs()
                 .map(|expr| Ok(expr.eval(vm)?.display_in_math()))
                 .collect::<SourceResult<_>>()?,
-        ))
+        )
+        .spanned(self.span()))
     }
 }