add error checking

scripts/xul2xhtml.sh

@@ -2,12 +2,12 @@
 GIT_REPO=https://gitlab.com/frg/seamonkey-central-patches.git
 rm -rf /tmp/comm-xul$$ /tmp/git-xul$$
 pushd /tmp
-hg clone https://hg.mozilla.org/comm-central/ /tmp/comm-xul$$
+hg clone https://hg.mozilla.org/comm-central/ /tmp/comm-xul$$ || exit 1
 if [ '$GIT_REPO' != '' ]
 then
   mkdir /tmp/git-xul$$
   cd /tmp/git-xul$$
-  git clone $GIT_REPO
+  git clone $GIT_REPO || exit 1
   cd /tmp/comm-xul$$
   if [ -s /tmp/git-xul$$/seamonkey-central-patches/comm-central/patches/series ]
   then
@@ -17,7 +17,7 @@ then
       then
         break
       fi
-      hg import /tmp/git-xul$$/seamonkey-central-patches/comm-central/patches/$i
+      hg import /tmp/git-xul$$/seamonkey-central-patches/comm-central/patches/$i || exit 1
     done
   fi
 fi