Sanitize terminal widget text

uiterm/tree.go

@@ -177,7 +177,7 @@ func (t *Tree) uiDraw() {
 			dx := x - t.x0
 			if reader != nil && level*2 <= dx {
 				if ch, _, err := reader.ReadRune(); err == nil {
-					chr = ch
+					chr = safeRune(ch)
 					fg, bg = item.TreeItemStyle(fg, bg, t.active && t.activeLine == line)
 				}
 			}