[Toybox] [PATCH 3/4] sh: fix bug in parameter substitution (pattern replacement)

[Alexander Holler]

Avoid a core dump on the following snippet:
  V="a.b"; V=${V//./}
---
 toys/pending/sh.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/toys/pending/sh.c b/toys/pending/sh.c
index 298bfbc0..c3c081a5 100644
--- a/toys/pending/sh.c
+++ b/toys/pending/sh.c
@@ -2149,7 +2149,7 @@ barf:
                 ll++;
                 continue;
               }
-              if (*delete && (*delete)->arg==ifs) {
+              if (delete && *delete && (*delete)->arg==ifs) {
                 if (jj==dd) memcpy(ifs+ll, ss, jj);
                 else if (jj<dd) sprintf(ifs+ll, "%s%s", ss, ifs+ll+dd);
                 else bird = ifs;
-- 
2.25.1