Improve build script error handling

Author: PhrozenByte

latest-version.sh

@@ -49,10 +49,10 @@ _xpath_url() {
 }
 
 echo + "curl -sSL $(quote "$DOWNLOADS_WEBPAGE_URL")" >&2
-DOWNLOADS_WEBPAGE="$(_curl "$DOWNLOADS_WEBPAGE_URL" | sed -e '1,/^$/d')"
+DOWNLOADS_WEBPAGE="$(_curl "$DOWNLOADS_WEBPAGE_URL" | sed -e '1,/^$/d' ||:)"
 [ -n "$DOWNLOADS_WEBPAGE" ] || { echo "Failed to request LimeSurvey downloads webpage: $DOWNLOADS_WEBPAGE_URL" >&2; exit 1; }
 
-ARCHIVE_URL="$(_xpath_url "$(sed -e 's#/[^/]*%s.*$#/#' <<< "$ARCHIVE_URL_TEMPLATE")" <<< "$DOWNLOADS_WEBPAGE")"
+ARCHIVE_URL="$(_xpath_url "$(sed -e 's#/[^/]*%s.*$#/#' <<< "$ARCHIVE_URL_TEMPLATE")" <<< "$DOWNLOADS_WEBPAGE" ||:)"
 [ -n "$ARCHIVE_URL" ] || { echo "Malformed LimeSurvey downloads webpage: $DOWNLOADS_WEBPAGE_URL" >&2; exit 1; }
 
 ARCHIVE_URL_REGEX="$(printf "$(sed -e 's/[]\/$*.^[]/\\&/g' <<< "$ARCHIVE_URL_TEMPLATE")" "$VERSION_REGEX")"