fix(PIDir): initialize list pointer and check scandir return

dirent** list was uninitialized, so scandir failure (returning -1)
left it with indeterminate value. The unconditional free(list) at
the end was then UB — typically heap corruption or crash.

libs/main/io_devices/pidir.cpp

@@ -372,7 +372,7 @@ PIVector<PIFile::FileInfo> PIDir::entries(const PIRegularExpression & regexp) {
 		closedir(dir);
 	}
 #  else
-	dirent ** list;
+	dirent ** list = nullptr;
 	int cnt        = scandir(p.data(),
                       &list,
                       0,
@@ -381,6 +381,7 @@ PIVector<PIFile::FileInfo> PIDir::entries(const PIRegularExpression & regexp) {
 #	else
 	                  versionsort);
 #	endif
+	if (cnt < 0) return ret;
 	for (int i = 0; i < cnt; ++i) {
 		ret << PIFile::fileInfo(dp + PIString(list[i]->d_name));
 		free(list[i]);