Correct error message typo

Signed-off-by: Gustaf Lundh <gustaflh@axis.com>

.changeset/good-scissors-doubt.md

@@ -0,0 +1,5 @@
+---
+'@backstage/backend-common': patch
+---
+
+Correct error message typo

packages/backend-common/src/service/lib/config.ts

@@ -78,7 +78,7 @@ export function readBaseOptions(config: Config): BaseOptions {
     typeof port !== 'string'
   ) {
     throw new Error(
-      `Invalid type in config for key 'backend.listen.post', got ${typeof port}, wanted string or number`,
+      `Invalid type in config for key 'backend.listen.port', got ${typeof port}, wanted string or number`,
     );
   }