Move isDefined from start-proxy to util

src/start-proxy.ts

@@ -2,7 +2,7 @@ import * as core from "@actions/core";
 
 import { KnownLanguage } from "./languages";
 import { Logger } from "./logging";
-import { ConfigurationError } from "./util";
+import { ConfigurationError, isDefined } from "./util";
 
 export type Credential = {
   type: string;
@@ -65,15 +65,6 @@ const LANGUAGE_TO_REGISTRY_TYPE: Partial<Record<KnownLanguage, string>> = {
   go: "goproxy_server",
 } as const;
 
-/**
- * Checks that `value` is neither `undefined` nor `null`.
- * @param value The value to test.
- * @returns Narrows the type of `value` to exclude `undefined` and `null`.
- */
-function isDefined<T>(value: T | null | undefined): value is T {
-  return value !== undefined && value !== null;
-}
-
 // getCredentials returns registry credentials from action inputs.
 // It prefers `registries_credentials` over `registry_secrets`.
 // If neither is set, it returns an empty array.

src/util.ts

@@ -1278,3 +1278,12 @@ export async function asyncSome<T>(
   const results = await Promise.all(array.map(predicate));
   return results.some((result) => result);
 }
+
+/**
+ * Checks that `value` is neither `undefined` nor `null`.
+ * @param value The value to test.
+ * @returns Narrows the type of `value` to exclude `undefined` and `null`.
+ */
+export function isDefined<T>(value: T | null | undefined): value is T {
+  return value !== undefined && value !== null;
+}