feat(registry): modernize npm registry file handling and package extraction APIs

ts/smartnpm.classes.registrycache.ts

@@ -12,6 +12,7 @@ export interface ICacheDescriptor {
 export class RegistryCache {
   npmregistryRef: NpmRegistry;
   public levelCache: plugins.levelcache.LevelCache;
+  public smartFileFactory = plugins.smartfile.SmartFileFactory.nodeFs();
 
   constructor(npmRegistryRefArg: NpmRegistry) {
     this.npmregistryRef = npmRegistryRefArg;
@@ -22,12 +23,12 @@ export class RegistryCache {
 
   public async getCachedFile(
     cacheDescriptorArg: ICacheDescriptor
-  ): Promise<plugins.smartfile.SmartFile> {
+  ): Promise<plugins.smartfile.SmartFile | null> {
     const cacheEntry = await this.levelCache.retrieveCacheEntryByKey(
       this.getCacheDescriptorAsString(cacheDescriptorArg)
     );
     if (cacheEntry) {
-      return plugins.smartfile.SmartFile.fromFoldedJson(cacheEntry.contents.toString());
+      return this.smartFileFactory.fromFoldedJson(cacheEntry.contents.toString());
     }
     return null;
   }
@@ -55,7 +56,7 @@ export class RegistryCache {
     }
   }
 
-  public getCacheDescriptorAsString(cacheDescriptorArg?: ICacheDescriptor) {
+  public getCacheDescriptorAsString(cacheDescriptorArg: ICacheDescriptor) {
     return `${cacheDescriptorArg.registryUrl}//+//${cacheDescriptorArg.packageName}//+//${
       cacheDescriptorArg.filePath
     }//+//${cacheDescriptorArg.distTag || cacheDescriptorArg.version}`;