Handle the case where "text_file" may be set, but the target file may be empty or missing. (#47)

Author: matthope

out

@@ -53,6 +53,7 @@ then
 fi
 
 export TEXT_FILE_CONTENT=""
+[[ -n "${text_file}" && ! -f "${text_file}" ]] && text_file=""
 [[ -n "${text_file}" && -f "${text_file}" ]] && TEXT_FILE_CONTENT="$(cat "${text_file}")"
 
 ATTACHMENTS_FILE_CONTENT=""