[check_config] refactor: improve error handling

[KristjanESPERANTO]

• Combine file existence and permission checks with better error messages
• Replace thrown exceptions with clean error output (no stack traces)
• Support custom module positions by changing strict validation to warnings
• Add missing process.exit(1) after validation errors

Users now see clear, actionable error messages without stack traces, and custom region configurations work correctly.

example before

$ npm run start

> [email protected] start
> node --run start:x11

[2025-10-22 17:56:06.303] [LOG]   Starting MagicMirror: v2.34.0-develop 
[2025-10-22 17:56:06.304] [LOG]   Loading config ... 
[2025-10-22 17:56:06.304] [LOG]   config template file not exists, no envsubst 
[2025-10-22 17:56:06.356] [ERROR] File not found: /home/kristjan/MagicMirror/config/config.js
No config file present! 
[2025-10-22 17:56:06.356] [ERROR] [checkconfig] Error: Error: ENOENT: no such file or directory, access '/home/kristjan/MagicMirror/config/config.js'
No permission to access config file!
    at checkConfigFile (/home/kristjan/MagicMirror/js/check_config.js:43:9)
    at Object.<anonymous> (/home/kristjan/MagicMirror/js/check_config.js:138:2)
    at Module._compile (node:internal/modules/cjs/loader:1714:14)
    at Module._extensions..js (node:internal/modules/cjs/loader:1848:10)
    at Module.load (node:internal/modules/cjs/loader:1448:32)
    at Module._load (node:internal/modules/cjs/loader:1270:12)
    at c._load (node:electron/js2c/node_init:2:17993)
    at TracingChannel.traceSync (node:diagnostics_channel:322:14)
    at wrapModuleLoad (node:internal/modules/cjs/loader:244:24)
    at Module.require (node:internal/modules/cjs/loader:1470:12)
    at require (node:internal/modules/helpers:147:16)
    at loadConfig (/home/kristjan/MagicMirror/js/app.js:126:3)
    at App.start (/home/kristjan/MagicMirror/js/app.js:291:18)
    at Object.<anonymous> (/home/kristjan/MagicMirror/js/electron.js:228:7)
    at Module._compile (node:internal/modules/cjs/loader:1714:14)
    at Module._extensions..js (node:internal/modules/cjs/loader:1848:10) 

example after

$ npm run start

> [email protected] start
> node --run start:x11

[2025-10-22 21:33:27.930] [LOG]   Starting MagicMirror: v2.34.0-develop 
[2025-10-22 21:33:27.931] [LOG]   Loading config ... 
[2025-10-22 21:33:27.931] [LOG]   config template file not exists, no envsubst 
[2025-10-22 21:33:27.985] [ERROR] [check_config] File not found: /home/kristjan/MagicMirror/config/config.js 

[rejas]

Users now see clearer, actionable error messages instead of unnecessary technical output (stack trace) when their config file has issues.

nice pr, but could we have an option that enables the stacktraces again (so one can still get them when needed)

maybe a command line param to enable it, since if it was a config.js option it might not work when check_config fails for some reason (since the config wouldnt have been loaded)

[KristjanESPERANTO]

nice pr, but could we have an option that enables the stacktraces again (so one can still get them when needed)

The stack traces are only removed for 'expected' validation errors (file not found, syntax error, invalid position) - with showing clean error messages there is no need of the stack trace, I think. The stack traces weren't providing useful debugging information, they just showed where we intentionally check for these errors.

For unexpected errors, there will be stack traces also after this change (the catch block at the bottom still logs them).

Should I nevertheless add a parameter?