ShapedText::push_hyphen: Use self.base for default hyphen range (#2299)

In the unlikely chance that we hyphenate after an empty line, we
set the glyph range to self.base..self.base so that subtracting

Fixes #2283.

1 files changed, 6 insertions, 1 deletions

diff --git a/crates/typst-library/src/text/shaping.rs b/crates/typst-library/src/text/shaping.rs
index 2d9dae33..57501c52 100644
--- a/crates/typst-library/src/text/shaping.rs
+++ b/crates/typst-library/src/text/shaping.rs
@@ -446,7 +446,12 @@ impl<'a> ShapedText<'a> {
                 .glyphs
                 .last()
                 .map(|g| g.range.end..g.range.end)
-                .unwrap_or_default();
+                // In the unlikely chance that we hyphenate after an
+                // empty line, ensure that the glyph range still falls
+                // after self.base so that subtracting either of the
+                // endpoints by self.base doesn’t underflow.
+                // See <https://github.com/typst/typst/issues/2283>.
+                .unwrap_or_else(|| self.base..self.base);
             self.width += x_advance.at(self.size);
             self.glyphs.to_mut().push(ShapedGlyph {
                 font,