Is Ticker.h really safe to use?
Update: the original question mentioned timers, so this answer is for a hardware timer interrupt handler. It doesn't apply to Ticker, which is what the question is now about.

The callback that you attach to blinker will be called as an interrupt handler, so it's important to make sure it's already loaded into executable instruction memory (iRAM) on the ESP8266. When you pass anonymous function inline to blinker.attach() it won't tagged to be stored in iRAM.

Try this instead:

void ICACHE_RAM_ATTR blinker_handler(){
    digitalWrite(LED,!(digitalRead(LED)));  //Toggle LED Pin
}

...

blinker.attach(1, blinker_handler);


ICACHE_RAM_ATTR tells the system to keep the code in the instruction RAM. There's not a lot of iRAM (32Kbytes) so you don't want to do this too often, but it's important for interrupt handlers (another reason to keep them short and sweet).