improved mutex error handling

- debug message in case of "unexpected" mutex errors
- removed experimental delay() in requestJSONBufferLock

wled00/wled.cpp

@@ -480,6 +480,8 @@ void WLED::setup()
   busDrawMux = xSemaphoreCreateRecursiveMutex();       // WLEDMM prevent concurrent running of strip.show and strip.service
   segmentMux = xSemaphoreCreateRecursiveMutex();       // WLEDMM prevent segment changes while effects are running
   jsonBufferLockMutex = xSemaphoreCreateRecursiveMutex(); // WLEDMM prevent concurrent JSON buffer writing
+  if ((busDrawMux == nullptr) || (segmentMux == nullptr) || (jsonBufferLockMutex == nullptr))
+    USER_PRINTLN(F("setup error: xSemaphoreCreateRecursiveMutex failed.")); // should never happen.
   xSemaphoreGiveRecursive(busDrawMux);                 // init semaphores to initially allow drawing
   xSemaphoreGiveRecursive(segmentMux);
   xSemaphoreGiveRecursive(jsonBufferLockMutex);