FS library position() to return (size_t) -1 on error (#10002)

* position_fix

Fix for error return from position()
Issue #9992

* ci(pre-commit): Apply automatic fixes

---------

Co-authored-by: pre-commit-ci-lite[bot] <117423508+pre-commit-ci-lite[bot]@users.noreply.github.com>

libraries/FS/src/FS.cpp

@@ -105,7 +105,7 @@ bool File::seek(uint32_t pos, SeekMode mode) {
 
 size_t File::position() const {
  if (!*this) {
- return 0;
+ return (size_t)-1;
  }
 
  return _p->position();

libraries/FS/src/FS.h

@@ -64,7 +64,7 @@ class File : public Stream {
  bool seek(uint32_t pos) {
  return seek(pos, SeekSet);
  }
- size_t position() const;
+ size_t position() const; // returns (size_t)-1 on error
  size_t size() const;
  bool setBufferSize(size_t size);
  void close();