fix a crash

Author: CppCXY

crates/emmylua_ls/src/handlers/completion/providers/mod.rs

@@ -156,7 +156,11 @@ fn get_text_edit_range_in_string(
     }
 
     if text.ends_with('"') || text.ends_with('\'') {
-        end_offset -= 1;
+        end_offset = end_offset.saturating_sub(1);
+    }
+
+    if end_offset <= start_offset {
+        return None;
     }
 
     let new_text_range = TextRange::new(start_offset.into(), end_offset.into());