refactor: consolidate remaining coercion helpers (#122020)

scripts/lib/cross-os-release-checks/shared.ts

@@ -1,6 +1,9 @@
 import { existsSync } from "node:fs";
 import { join } from "node:path";
 import { truncateUtf16Safe } from "../../../packages/normalization-core/src/utf16-slice.ts";
+import { toErrorObject as toLintErrorObject } from "../error-format.mts";
+
+export { toLintErrorObject };
 
 export function resolveCommandPath(command: string) {
   const pathValue = process.env.PATH ?? "";
@@ -44,17 +47,3 @@ export function sleep(ms: number) {
     setTimeout(resolvePromise, ms);
   });
 }
-
-export function toLintErrorObject(value: unknown, fallbackMessage: string): Error {
-  if (value instanceof Error) {
-    return value;
-  }
-  if (typeof value === "string") {
-    return new Error(value);
-  }
-  const error = new Error(fallbackMessage, { cause: value });
-  if ((typeof value === "object" && value !== null) || typeof value === "function") {
-    Object.assign(error, value);
-  }
-  return error;
-}

scripts/lib/error-format.mts

@@ -6,3 +6,23 @@ export function formatErrorMessage(error: unknown): string {
   }
   return String(error);
 }
+
+/** Read Error messages unchanged and stringify every other value. */
+export function coerceErrorMessage(value: unknown): string {
+  return value instanceof Error ? value.message : String(value);
+}
+
+/** Preserve structured non-Error failures without requiring built workspace packages. */
+export function toErrorObject(value: unknown, fallbackMessage: string): Error {
+  if (value instanceof Error) {
+    return value;
+  }
+  if (typeof value === "string") {
+    return new Error(value);
+  }
+  const error = new Error(fallbackMessage, { cause: value });
+  if ((typeof value === "object" && value !== null) || typeof value === "function") {
+    Object.assign(error, value);
+  }
+  return error;
+}