pagermon: TypeError: Cannot read property '1' of null

Crashed today with this message. Running on Raspberry Pi.

readline.js:1032
            throw err;
            ^

TypeError: Cannot read property '1' of null
    at Interface.rl.on (/home/pi/pagermon/client/reader.js:104:48)
    at Interface.emit (events.js:189:13)
    at Interface._onLine (readline.js:290:10)
    at Interface._line (readline.js:638:8)
    at Interface._ttyWrite (readline.js:926:16)
    at Socket.onkeypress (readline.js:168:10)
    at Socket.emit (events.js:189:13)
    at emitKeys (internal/readline.js:424:14)
    at emitKeys.next (<anonymous>)
    at Socket.onData (readline.js:1022:36)
Signal caught, exiting!

User cancel, exiting...

About this issue

Original URL
State: closed
Created 5 years ago
Comments: 15 (2 by maintainers)

Commits related to this issue

Adds try/catch to prevent "TypeError: Cannot read property '1' of null" error from killing the script. Error is caused by unexpected formatting of pager messages, which needs to be expanded upon. Issu... — committed to CramShack/pagermon by deleted user 2 years ago

Most upvoted comments

replace line 121 of reader.js with the following message = line.match(/FLEX[:|].*[|\[][0-9 ]*[|\]] ?...[ |]{0,1}(.*)/)[1].trim();

I was only given one example of a message that causes this and slightly modified the regex so that [1] is always defined. I actually did that back in 2021 and with the single example provided, it fixed the issue.

You can see here with new regex, the line matches and group 1 is defined, but empty: https://regex101.com/r/S8HMZv/1 This is the old regex, where group 1 is undefined, because the regex doesn’t match at all: https://regex101.com/r/BdxbfY/1

There was a PR that involved wrapping statements in try/catch, but i dont think it was finished. Then reader.js was rewritten and I lost track of who was doing what. Anyway, that will solve it.

If you want to prevent reader.sh from stopping when it encounters an error, you can also do this (where … is your existing config, just add “do” to the start of that line):

while true;
do rtl-fm ... | node reader.js;
sleep 10;
done

that will restart the reader after a 10 second delay if something causes it to fail

geelongmicrosoldering on May 20, 2023