Fix 'attempt to divide by zero' panic (#6155)

helix-term/src/ui/text.rs

@@ -58,7 +58,7 @@ pub fn required_size(text: &tui::text::Text, max_text_width: u16) -> (u16, u16)
         let content_width = content.width() as u16;
         if content_width > max_text_width {
             text_width = max_text_width;
-            height += content_width / max_text_width;
+            height += content_width.checked_div(max_text_width).unwrap_or(0);
         } else if content_width > text_width {
             text_width = content_width;
         }