patch 9.1.0730: Crash with cursor-screenline and narrow window

Problem:  Crash with cursor-screenline and narrow window
          (elig0n)
Solution: Don't set right_col when width2 is 0 (zeertzjq).

fixes: #15677
closes: #15678

Signed-off-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/drawline.c b/src/drawline.c
index b627192..fd5d56b 100644
--- a/src/drawline.c
+++ b/src/drawline.c
@@ -62,7 +62,7 @@
     *left_col = 0;
     *right_col = width1;
 
-    if (wp->w_virtcol >= (colnr_T)width1)
+    if (wp->w_virtcol >= (colnr_T)width1 && width2 > 0)
 	*right_col = width1 + ((wp->w_virtcol - width1) / width2 + 1) * width2;
     if (wp->w_virtcol >= (colnr_T)width1 && width2 > 0)
 	*left_col = (wp->w_virtcol - width1) / width2 * width2 + width1;