fix: modules losing data after HTTP 304 responses - #4180
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When a calendar server responds with 304 (nothing changed since last fetch), the response has no body. CalendarFetcher was parsing it anyway, which produced an empty event list - clearing all previously loaded events and showing nothing on screen. The bug was hidden until MagicMirrorOrg#4120 started forwarding 304 responses through HTTPFetcher instead of silently dropping them. Fix: skip parsing on 304 and re-broadcast the cached events as-is. Also adding unit tests for CalendarFetcher: 304 handling, HTTP error forwarding, parse error resilience, and shouldRefetch boundaries.
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## Release Notes Thanks to: @angeldeejay, @egeekial, @khassel, @KristjanESPERANTO, @MikeBishop, @rejas >⚠️ This release needs nodejs version >=22.21.1 <23 || >=24 (no change to previous release) [Compare to previous Release v2.36.0](v2.36.0...develop) ### [core] - Prepare Release 2.37.0 (#4193) - fix(electron): map IPv6 :: wildcard to localhost (#4188) - refactor(main): modernize DOM update flow with async/await (#4186) - refactor(main): simplify _updateDom with async/await (#4185) - fix(security): prevent unauthorized secret expansion in socket payloads (#4184) - refactor(main): simplify updateDomWithContent async flow (#4182) - fix: modules losing data after HTTP 304 responses (#4180) - chore: add missing core defaults (#4181) - fix(server): enforce ipWhitelist for Socket.IO too (#4169) - feat(systeminfo): include Git hash and branch in system information log (#4167) - feat(electron): support object-based electronSwitches (#4161) - systeminformation thread not ending: move error handling from utils to app (#4160) - fix systeminformation thread not ending (#4155) - refactor: use ES module imports in browser core (#4158) - refactor(core): remove old Object.assign polyfill (#4157) - refactor: rewrite Module as an ES6 class (#4151) - refactor: rewrite NodeHelper as an ES6 class (#4147) - update eletron to v42 (#4144) - refactor(utils): drop ajv dependency (#4142) - fix(systeminformation): output right 'used node' version (from parent process) (#4141) - fix: skip postinstall git clean when not in a git repository (#4139) - Remove unnecessary conditionals and fix falsy property check in imperial conversion (#4135) - update version in package.json ### [dependencies] - update dependencies (#4191) - Bump actions/checkout from 6 to 7 (#4190) - chore: update dependencies and adjust import path for SunCalc (#4189) - update dependencies incl. electron and revert yauzl-electron-install-fix (#4183) - update dependencies, add electron fix in package.json (#4175) - chore: update dependencies (#4162) - Bump actions/dependency-review-action from 4 to 5 (#4152) - Unify linting: replace Stylelint and markdownlint with ESLint (#4148) - update dependencies and workflows to node v26 (#4140) ### [modules/alert] - CodeQL cleanup for alerts #18, #19, #20 (#4153) - fix: resolve CodeQL alerts #24 and #26 (#4145) - fix(electron): resolve CodeQL alerts #22 and #25 in electron.js (#4136) ### [modules/calendar] - perf(calendar): pre-filter ICS data before parsing (#4168) - perf(calendar): use async ICS parsing to avoid blocking event loop (#4143) ### [modules/newsfeed] - [newsfeed] add allowBasicHtmlTags option for basic emphasis (#4176) ### [modules/updatenotification] - fix(updatenotification): don't spawn a child process when running under PM2 (#4166) - fix(updatenotification): use process.argv[0] as restart binary (#4163) - fix(updatenotification): preserve start mode on restart (#4156) - fix(updatenotification): fix ref diff parsing for fetch --dry-run (#4138) - refactor(updatenotification): replace pm2 usage with node logic (#4134) ### [modules/weather] - feat(weather): add Buienradar provider (#4164) ### [testing] - remove warning in unit tests (for nodejs >= v25) (#4149) - polish HTTP 304 docs/test/handling (#4129) --------- Signed-off-by: dependabot[bot] <support@github.com> Co-authored-by: Kristjan ESPERANTO <35647502+KristjanESPERANTO@users.noreply.github.com> Co-authored-by: BugHaver <43462320+bughaver@users.noreply.github.com> Co-authored-by: BugHaver <43462320+lsaadeh@users.noreply.github.com> Co-authored-by: Karsten Hassel <hassel@gmx.de> Co-authored-by: Magnus <34011212+MagMar94@users.noreply.github.com> Co-authored-by: Koen Konst <koenspero@gmail.com> Co-authored-by: Koen Konst <c.h.konst@avisi.nl> Co-authored-by: Bugsounet - Cédric <github@bugsounet.fr> Co-authored-by: dathbe <github@beffa.us> Co-authored-by: veeck <gitkraken@veeck.de> Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com> Co-authored-by: Marcel <m-idler@users.noreply.github.com> Co-authored-by: sam detweiler <sdetweil@gmail.com> Co-authored-by: Kevin G. <crazylegstoo@gmail.com> Co-authored-by: Jboucly <33218155+jboucly@users.noreply.github.com> Co-authored-by: Jboucly <contact@jboucly.fr> Co-authored-by: Jarno <54169345+jarnoml@users.noreply.github.com> Co-authored-by: Jordan Welch <JordanHWelch@gmail.com> Co-authored-by: Blackspirits <blackspirits@gmail.com> Co-authored-by: Samed Ozdemir <samed@xsor.io> Co-authored-by: in-voker <58696565+in-voker@users.noreply.github.com> Co-authored-by: Andrés Vanegas Jiménez <142350+angeldeejay@users.noreply.github.com> Co-authored-by: cgillinger <christian.gillinger@gmail.com> Co-authored-by: Sonny B <43247590+sonnyb9@users.noreply.github.com> Co-authored-by: sonnyb9 <sonnyb9@users.noreply.github.com> Co-authored-by: Morgan McBee <egeekial@users.noreply.github.com> Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com> Co-authored-by: Mike Bishop <mbishop@evequefou.be>
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When a server responds with 304 (nothing changed since last fetch), the response has no body. Several modules were trying to parse that empty body anyway - which either cleared their cached data or threw an exception. The result: a blank calendar, empty newsfeed, or missing weather data after the next refresh cycle.
This was reported in the forum: https://forum.magicmirror.builders/topic/20250/calendar-events-broadcasting-nothing-showing
The bug was "introduced" by #4120, which correctly started forwarding 304s to consumers - but not all were ready for it.
Fix
Skip parsing on 304 and keep the existing data as-is:
response.json()