The showcase doesn't start locally when running yarn start

[Zaperex]

Describe the bug

When using yarn start in the root directory to start the backstage application, the frontend fails with the following error:

When testing doing yarn start from commit 4a6266e (before the 1.22 upgrade)
The logs produce the following and backstage starts up properly:

backend:start: cache bypass, force executing f3913656802e2f5f
@internal/plugin-dynamic-plugins-info-backend:start: cache bypass, force executing fd38329a4c7ee316
@internal/plugin-scalprum-backend:start: cache bypass, force executing 87683b206ad30f9b
app:start: cache bypass, force executing 6c746a5d57ae5faf
backend:start: $ cross-env LEGACY_BACKEND_START=true backstage-cli package start
@internal/plugin-scalprum-backend:start: $ backstage-cli package start
@internal/plugin-dynamic-plugins-info-backend:start: $ backstage-cli package start
app:start: $ janus-cli package start
@internal/plugin-scalprum-backend:start: (node:211262) ExperimentalWarning: Custom ESM Loaders is an experimental feature and might change at any time
@internal/plugin-scalprum-backend:start: (Use `node --trace-warnings ...` to show where the warning was created)
@internal/plugin-dynamic-plugins-info-backend:start: (node:211263) ExperimentalWarning: Custom ESM Loaders is an experimental feature and might change at any time
@internal/plugin-dynamic-plugins-info-backend:start: (Use `node --trace-warnings ...` to show where the warning was created)
backend:start: Build succeeded

The logs start returning the following when switching to the backstage 1.22.1 commit 8f9811c, but the showcase still starts properly.

app:start: cache bypass, force executing f6333405e07da288
@internal/plugin-dynamic-plugins-info-backend:start: cache bypass, force executing 94c6b8fd02e56c01
@internal/plugin-scalprum-backend:start: cache bypass, force executing 6d2932d82f85349e
backend:start: cache bypass, force executing 243cea59deea3070
@internal/plugin-dynamic-plugins-info-backend:start: $ backstage-cli package start
backend:start: $ cross-env LEGACY_BACKEND_START=true backstage-cli package start
app:start: $ janus-cli package start
@internal/plugin-scalprum-backend:start: $ backstage-cli package start
@internal/plugin-dynamic-plugins-info-backend:start: The 'dev' directory is missing. Please create a proper dev/index.ts in order to start the plugin.
@internal/plugin-scalprum-backend:start: The 'dev' directory is missing. Please create a proper dev/index.ts in order to start the plugin.
backend:start: Build succeeded

The last commit that still worked was 6b8b82c.

The issue starts occurring at commit ebebc0a from "chore(deps): update all non-major dependencies (#693)"

Expected Behavior

The backstage showcase starts up properly when running yarn start

What are the steps to reproduce this bug?

1. Checkout to ebebc0a or later
2. run yarn start
3. Observe frontend failing with Error Scalprum was not initialized! Call the initialize function first.

Versions of software used and environment

https://github.com/janus-idp/backstage-showcase/tree/4f1c1b60489450647b8102083c3ae55d2cb05049
node v18.18.0 (also tested with node v18.19.0 and issue persists)
yarn v1.22.19

[Zaperex]

It seems to work after doing a git revert ebebc0acef5e0362c9001271c0e6df38370a2d23 to revert ebebc0a

[Zaperex]

A function we used was actually deprecated and removed in v0.7.0 of @scalprum/core
https://github.com/scalprum/scaffolding/pull/114/files#diff-16951a076f27175290484178ab8a33bbdf697b9ac96cac8390134042b4789dd2L34-L36

[Zaperex]

Fixed by #915.
Next steps is to potentially see if we can update the DynamicRoot to use the new transformPluginManifest function instead of the deprecated postProcessManifest that is currently in use.