Fix empty constructor for Dir object in DOSFS

Author: GrumpyOldPizza

cores/stm32l4/FS.cpp

@@ -140,6 +140,11 @@ Dir::Dir(const char* path) {
     }
 }
 
+Dir::Dir() {
+    _path[0] = '\0';
+    _find.find_clsno = 0x0fffffff;
+};
+
 File Dir::openFile(const char* mode) {
     char filename[F_MAXPATH];
 

cores/stm32l4/FS.h

@@ -66,7 +66,7 @@ class File : public Stream
 class Dir {
 public:
     Dir(const char *path);
-    ~Dir();
+    Dir();
 
     File openFile(const char* mode);
     String fileName();