Adding check for cache paths' existence.

src/cache.ts

@@ -158,6 +158,12 @@ export async function saveCache(
   core.debug('Cache Paths:')
   core.debug(`${JSON.stringify(cachePaths)}`)
 
+  
+  if(cachePaths.length === 0){
+    throw new ValidationError(
+      `Path Validation Error: Path(s) specified in the action do not exist, hence no cache is being saved.`)
+  }
+
   const archiveFolder = await utils.createTempDirectory()
   const archivePath = path.join(
     archiveFolder,