<format>: Use _STL_INTERNAL_CHECK for calls of to_chars (#3697)

These `to_chars` should never fail unless there's a bug in the implementation, so it's more appropriate to use `_STL_INTERNAL_CHECK`.

Author: cpplearner

stl/inc/format

@@ -2417,7 +2417,7 @@ inline namespace __p2286 {
 
         if (_End == _Buffer) {
             const to_chars_result _Result = _STD to_chars(_Buffer, _STD end(_Buffer), _Value);
-            _STL_ASSERT(_Result.ec == errc{}, "to_chars failed");
+            _STL_INTERNAL_CHECK(_Result.ec == errc{});
             _End = _Result.ptr;
         }
 
@@ -2444,7 +2444,7 @@ inline namespace __p2286 {
         // TRANSITION, Reusable buffer
         char _Buffer[_Format_min_buffer_length];
         const auto [_End, _Ec] = _STD to_chars(_Buffer, _STD end(_Buffer), reinterpret_cast<uintptr_t>(_Value), 16);
-        _STL_ASSERT(_Ec == errc{}, "to_chars failed");
+        _STL_INTERNAL_CHECK(_Ec == errc{});
         *_Out++ = '0';
         *_Out++ = 'x';
         return _Widen_and_copy<_CharT>(_Buffer, _End, _STD move(_Out));
@@ -2710,7 +2710,7 @@ inline namespace __p2286 {
         // long long -1 representation in binary is 64 bits + sign
         char _Buffer[65];
         const auto [_End, _Ec] = _STD to_chars(_Buffer, _STD end(_Buffer), _Value, _Base);
-        _STL_ASSERT(_Ec == errc{}, "to_chars failed");
+        _STL_INTERNAL_CHECK(_Ec == errc{});
 
         auto _Buffer_start = _Buffer;
         auto _Width        = static_cast<int>(_End - _Buffer_start);
@@ -2916,7 +2916,7 @@ inline namespace __p2286 {
                 _Result = _STD to_chars(_Buffer, _STD end(_Buffer), _Value, _Format, _Precision);
             }
 
-            _STL_ASSERT(_Result.ec == errc{}, "to_chars failed");
+            _STL_INTERNAL_CHECK(_Result.ec == errc{});
         }
 
         auto _Buffer_start = _Buffer;