backend-plugin-api: tighten internal any usage (#33867)

* backend-plugin-api: tighten internal any usage

Replace internal `any` type annotations with proper types:

- Use `'root' | 'plugin'` union in DepsToInstances conditional type
  and createServiceRef implementation signature
- Use Error type guard with object cast fallback in
  isDatabaseConflictError instead of `as any`

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>
Made-with: Cursor

* Use isError in isDatabaseConflictError

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>
Made-with: Cursor

* Update changeset wording per review feedback

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>
Made-with: Cursor

---------

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>

.changeset/tighten-internal-any-usage.md

@@ -0,0 +1,5 @@
+---
+'@backstage/backend-plugin-api': patch
+---
+
+Added stricter type checks in `isDatabaseConflictError`.

packages/backend-plugin-api/src/services/system/types.ts

@@ -136,8 +136,8 @@ export function createServiceRef<
   TService,
   TInstances extends 'singleton' | 'multiton',
 >(
-  options: ServiceRefOptions<TService, any, TInstances>,
-): ServiceRef<TService, any, TInstances> {
+  options: ServiceRefOptions<TService, 'root' | 'plugin', TInstances>,
+): ServiceRef<TService, 'root' | 'plugin', TInstances> {
   const { id, scope = 'plugin', multiton = false, defaultFactory } = options;
   return {
     id,

packages/backend-plugin-api/src/services/utilities/database.ts

@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+import { isError } from '@backstage/errors';
+
 /**
  * Tries to deduce whether a thrown error is a database conflict.
  *
@@ -23,7 +25,7 @@
  *          known database engine
  */
 export function isDatabaseConflictError(e: unknown) {
-  const message = (e as any)?.message;
+  const message = isError(e) ? e.message : undefined;
 
   return (
     typeof message === 'string' &&

packages/backend-plugin-api/src/wiring/types.ts

@@ -56,7 +56,11 @@ type DepsToInstances<
     [key in string]: ServiceRef<unknown> | ExtensionPoint<unknown>;
   },
 > = {
-  [key in keyof TDeps]: TDeps[key] extends ServiceRef<unknown, any, 'multiton'>
+  [key in keyof TDeps]: TDeps[key] extends ServiceRef<
+    unknown,
+    'root' | 'plugin',
+    'multiton'
+  >
     ? Array<TDeps[key]['T']>
     : TDeps[key]['T'];
 };