fix(manifest sign): --private-key option is required and validated

JST-386

src/lib/file.ts

@@ -21,3 +21,13 @@ export async function checkFileOverwrite(
     // File does not exist, that's fine.
   }
 }
+
+export async function assertFileExists(name: string, path: string): Promise<void> {
+  try {
+    await stat(path);
+  } catch (e) {
+    // File does not exist, that's fine.
+    console.error(`Error: ${name} "${path}" not found.`);
+    process.exit(1);
+  }
+}

src/manifest/manifest-sign.action.ts

@@ -2,10 +2,12 @@ import { ManifestSignOptions } from "./manifest-sign.options";
 import { readManifest } from "./manifest-utils";
 import { readFile, writeFile } from "fs/promises";
 import { createSign } from "crypto";
+import { assertFileExists } from "../lib/file";
 
 export async function manifestSignAction(options: ManifestSignOptions): Promise<void> {
   // Read and validate the manifest.
   await readManifest(options.manifest);
+  await assertFileExists("Private key file", options.keyFile);
 
   // Read manifest buffer.
   const manifestBuffer = await readFile(options.manifest);

src/manifest/manifest-sign.command.ts

@@ -6,7 +6,7 @@ export const manifestSignCommand = new Command("sign");
 manifestSignCommand
   .description("Sign Golem manifest file.")
   .addOption(createManifestOption())
-  .option("-k, --key-file <file>", "Private key file.")
+  .requiredOption("-k, --key-file <file>", "Private key file.")
   .option("-p, --passphrase <passphrase>", "Passphrase for the private key.")
   .option("-s, --signature-file <file>", "Signature file.", "manifest.sig")
   .action(async (options: ManifestSignOptions) => {