Stop the watcher when the connector output it watches can't be read

The output file was checked once, before polling. If it went away later,
wc failed, the line count read as zero, and the watcher slept forever while
looking alive. Each poll now checks the file and exits 2 if it can't be read.

Author: robzolkos

skills/basecamp-connect/watch-requests.sh

@@ -25,6 +25,10 @@ fi
 
 unhandled() {
   local lines
+  if [ ! -r "$out" ]; then
+    echo "watch-requests: can't read the connector output at $out" >&2
+    exit 2
+  fi
   lines=$(($(wc -l < "$out")))
   [ "$lines" -gt 0 ] || return 1
   head -n "$lines" "$out" | HANDLED=$handled awk '