setWatch on ESP8266 is not stable ?!

@hungryforcodes, @allObjects, thanks for the reply. I use ESP-07 from Ai. Now, I am developing lamp controller that can be remotely controlled by MQTT protocol. However, I want to use the previously mechanical switch to control the lamp, locally, in case the network failed. I connected directly the mechanical switch to pin D5 of esp8266 tied-up with 10K resistor to VCC. It seems that the problem is the mechanical switch. I have tested the code below :

print("Starting watch set test\n");
var testPin = D13;
pinMode(testPin, "input");
var watchId = setWatch(function() {
  print("The callback function was called for a pin I/O change\n");
}, testPin, { repeat: true} );
print("A new watch was set up with id=" + watchId + "\n");

And the result is there are many callback function was called, and the ESp8266 was crashed.

then I put a small capacitor on the switch terminal, and add debounce at 100, then it is run well.
Thanks for your attention.