From 0f55f70b445202fd9d3c101b9936e6649e808441 Mon Sep 17 00:00:00 2001
From: Yunbo Ni <87902024+cardigan1008@users.noreply.github.com>
Date: Mon, 29 Jul 2024 18:46:40 +0800
Subject: [PATCH] Fix unwrap panic in next_boundary() (#137)

---
 src/grapheme.rs | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/grapheme.rs b/src/grapheme.rs
index be88b48..b09efed 100644
--- a/src/grapheme.rs
+++ b/src/grapheme.rs
@@ -694,8 +694,11 @@ impl GraphemeCursor {
         if self.offset == self.len {
             return Ok(None);
         }
-        let mut iter = chunk[self.offset - chunk_start..].chars();
-        let mut ch = iter.next().unwrap();
+        let mut iter = chunk[self.offset.saturating_sub(chunk_start)..].chars();
+        let mut ch = match iter.next() {
+            Some(ch) => ch,
+            None => return Err(GraphemeIncomplete::NextChunk),
+        };
         loop {
             if self.resuming {
                 if self.cat_after.is_none() {