Update verify.ts

Proposed fix from coderabbitai

Author: tcely

src/verify.ts

@@ -6,6 +6,9 @@ import { fetchAssetMetadata, getHexFromDigest } from "./github-asset";
 import { getVerifiedManifest } from "./manifest";
 import { getGitHubManifestUrl } from "./url";
 
+class DigestVerificationError extends Error {}
+class UnsupportedAlgorithmError extends Error {}
+
 interface AlgorithmConfig {
   readonly manifestFile: string;
 }
@@ -32,7 +35,7 @@ function getManifest(algoName: string): string {
     return supportedAlgorithms[algoName].manifestFile;
   }
 
-  throw new Error(`Unsupported algorithm: ${algoName}`);
+  throw new UnsupportedAlgorithmError(`Unsupported algorithm: ${algoName}`);
 }
 
 /**
@@ -91,7 +94,9 @@ export async function verifyAsset(
     const updatedAt = new Date(metadata.updated_at);
     if (Number.isNaN(updatedAt.getTime())) {
       silentUnlink(zipPath);
-      throw new Error(`Invalid updated_at for asset ${assetName}`);
+      throw new DigestVerificationError(
+        `Invalid updated_at for asset ${assetName}`,
+      );
     }
 
     /**
@@ -105,20 +110,20 @@ export async function verifyAsset(
         const githubHash = getHexFromDigest(metadata.digest);
         if (githubHash !== actualHash) {
           silentUnlink(zipPath);
-          throw new Error(
+          throw new DigestVerificationError(
             `Security Mismatch: GitHub API digest (${githubHash}) differs from local hash (${actualHash})!`,
           );
         }
         digest_matched = true;
         info(`GitHub API digest matched! (${metadata.digest})`);
       } else {
         warning(
-          `GitHub digest missing for asset updated on ${metadata.updated_at.toISOString()}`,
+          `GitHub digest missing for asset updated on ${updatedAt.toISOString()}`,
         );
       }
     }
   } catch (err) {
-    if (err instanceof Error && err.message.startsWith("Security Mismatch:")) {
+    if (err instanceof DigestVerificationError) {
       throw err; // always propagate real mismatches
     }
     warning(`Skipping GitHub API digest check for: ${downloadUrl}`);