Fix types for errors

src/cache-save.ts

@@ -17,7 +17,7 @@ export async function run() {
     const cacheLock = core.getInput('cache');
     await cachePackages(cacheLock);
   } catch (error) {
-    core.setFailed(error.message);
+    core.setFailed((error as Error).message);
   }
 }
 

src/main.ts

@@ -72,7 +72,7 @@ export async function run() {
       `##[add-matcher]${path.join(matchersPath, 'eslint-compact.json')}`
     );
   } catch (err) {
-    core.setFailed(err.message);
+    core.setFailed((err as Error).message);
   }
 }