Merge pull request #33720 from backstage/rugvip/add-to-error-utility

errors: add `toError` utility and migrate usages

.changeset/add-to-error-utility.md

@@ -0,0 +1,5 @@
+---
+'@backstage/errors': minor
+---
+
+A new `toError` utility function is now available for converting unknown values to `ErrorLike` objects. If the value is already error-like it is returned as-is, strings are used directly as the error message, and all other values are wrapped as `unknown error '<stringified>'`. Non-error causes passed to `CustomErrorBase` are now converted and stored using `toError` rather than discarded.

.changeset/deep-ripe-rats.md

@@ -0,0 +1,30 @@
+---
+'@backstage/backend-app-api': patch
+'@backstage/backend-defaults': patch
+'@backstage/cli': patch
+'@backstage/cli-common': patch
+'@backstage/cli-module-migrate': patch
+'@backstage/cli-module-new': patch
+'@backstage/cli-node': patch
+'@backstage/config-loader': patch
+'@backstage/core-components': patch
+'@backstage/repo-tools': patch
+'@backstage/plugin-auth': patch
+'@backstage/plugin-auth-backend': patch
+'@backstage/plugin-catalog': patch
+'@backstage/plugin-catalog-backend': patch
+'@backstage/plugin-catalog-backend-module-incremental-ingestion': patch
+'@backstage/plugin-catalog-import': patch
+'@backstage/plugin-catalog-react': patch
+'@backstage/plugin-catalog-unprocessed-entities': patch
+'@backstage/plugin-devtools-backend': patch
+'@backstage/plugin-mcp-actions-backend': patch
+'@backstage/plugin-notifications-backend-module-slack': patch
+'@backstage/plugin-scaffolder-backend': patch
+'@backstage/plugin-scaffolder-backend-module-github': patch
+'@backstage/plugin-search-backend-node': patch
+'@backstage/plugin-techdocs-backend': patch
+'@backstage/plugin-techdocs-node': patch
+---
+
+Migrated from `assertError` to `toError` for error handling.