Do not swallow errors from session-data-defaults.js

[fofr]

If the code generating session-data-defaults is fairly complex, spotting and fixing those errors is a common problem, and is more than fixing simple syntax issues.

This change still allows the app to run, but will show the original error in the console alongside the warning about loading the defaults. By showing the full error it also highlights where there's a problem – the single line "Could not load…" message can be easily missed in a busy log.

Showing the error in the log allows a developer to debug and fix the problem.

[joelanman]

thanks! Would you mind pasting a sample terminal output when there's an error?

[fofr]

@joelanman Sure, it's a standard stack-trace, so looks like this (I threw in a random error – I gave an object a trailing comma it should not have – and I can see that it's on line 14 of session-data-defaults).

Console before

[10:17:40] [nodemon] starting `node listen-on-port.js`
Could not load the session data defaults from app/data/session-data-defaults.js. Might be a syntax error?

GOV.UK Prototype Kit v9.3.0

NOTICE: the kit is for building prototypes, do not use it for production services.

Listening on port 3003   url: http://localhost:3003

Console after

[10:17:40] [nodemon] starting `node listen-on-port.js`
Could not load the session data defaults from app/data/session-data-defaults.js.
/app/data/session-data-defaults.js:14
const sessionCases = [
^^^^^

SyntaxError: Unexpected token 'const'
    at wrapSafe (internal/modules/cjs/loader.js:1053:16)
    at Module._compile (internal/modules/cjs/loader.js:1101:27)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1157:10)
    at Module.load (internal/modules/cjs/loader.js:985:32)
    at Function.Module._load (internal/modules/cjs/loader.js:878:14)
    at Module.require (internal/modules/cjs/loader.js:1025:19)
    at require (internal/modules/cjs/helpers.js:72:18)
    at Object.<anonymous> (lib/utils.js:270:25)
    at Module._compile (internal/modules/cjs/loader.js:1137:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1157:10)

GOV.UK Prototype Kit v9.3.0

NOTICE: the kit is for building prototypes, do not use it for production services.

Listening on port 3003   url: http://localhost:3003

[edwardhorsford]

I think this solves #793

[edwardhorsford]

Any reason not to prevent the app running? That might be more obvious that something has gone wrong.

[joelanman]

maybe a newline \n between the message and the error might be a small thing to help with readability

[fofr]

Any reason not to prevent the app running? That might be more obvious that something has gone wrong.

I didn't want to change existing behaviour

[fofr]

@joelanman I didn't add a newline as the two things relate to each other, whereas elsewhere in the log the new lines distinguish separate things (like the kit version and the port being used)

[lfdebrux]

Looks good to me 👍

[joelanman]

in that case we just need to add a line for this in the changelog - are you ok to add that @fofr ?

[fofr]

👍 @joelanman I've added a changelog entry

[36degrees]

Thanks, @fofr 👍🏻