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

@@ -372,15 +372,16 @@ PIVector<PIFile::FileInfo> PIDir::entries(const PIRegularExpression & regexp) {
 		closedir(dir);
 	}
 #  else
-	dirent ** list;
-	int cnt = scandir(p.data(),
-	                  &list,
-	                  0,
+	dirent ** list = nullptr;
+	int cnt        = scandir(p.data(),
+                      &list,
+                      0,
 #	if defined(MAC_OS) || defined(ANDROID) || defined(BLACKBERRY)
-	                  alphasort);
+                      alphasort);
 #	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]);