using std::nothrow instead of malloc (#6251)

Author: d-a-v

cores/esp8266/Schedule.cpp

@@ -45,14 +45,9 @@ static scheduled_fn_t* get_fn_unsafe ()
     // if no unused items, and count not too high, allocate a new one
     else if (sCount < SCHEDULED_FN_MAX_COUNT)
     {
-        // calling malloc instead of new to avoid exception raising while in ISR
-        // construct complex members in place (never raises exceptions)
-        result = (scheduled_fn_t*)malloc(sizeof(scheduled_fn_t));
+        result = new (std::nothrow) scheduled_fn_t;
         if (result)
-        {
-            new (&result->mFunc) decltype(result->mFunc)();
             ++sCount;
-        }
     }
     return result;
 }
@@ -91,7 +86,7 @@ bool schedule_recurrent_function_us (const std::function<bool(void)>& fn, uint32
 
     esp8266::InterruptLock lockAllInterruptsInThisScope;
 
-    recurrent_fn_t* item = new recurrent_fn_t(repeat_us);
+    recurrent_fn_t* item = new (std::nothrow) recurrent_fn_t(repeat_us);
     if (!item)
         return false;