Fix segfault in prt-cache

Co-authored-by: Alexandr Savca <alexandr.savca89@gmail.com>

src/prtget.cpp

@@ -1806,6 +1806,11 @@ void PrtGet::ls()
     if ( p ) {
         string dirname = p->path() + "/" + p->name();
         DIR* dir = opendir(dirname.c_str());
+        if (dir == NULL) {
+                cerr << "Directory " << dirname << " not found" << endl;
+                m_returnValue = PG_GENERAL_ERROR;
+                return;
+        }
         struct dirent* entry;
         vector<string> files;
         while ((entry = readdir(dir))) {
@@ -1848,7 +1853,7 @@ void PrtGet::cat()
         }
         string file = p->path() + "/" + p->name() + "/" + fileName;
         if (!printFile(file)) {
-            cerr << "File '" << *it << "' not found" << endl;
+            cerr << "File '" << fileName << "' not found" << endl;
             m_returnValue = PG_GENERAL_ERROR;
             return;
         }