This code will crash your watch.

anim_schedule.c

#include "pebble_os.h"
#include "pebble_app.h"
#include "pebble_fonts.h"


#define MY_UUID { 0xF7, 0x58, 0xEF, 0x93, 0x27, 0xBB, 0x4F, 0x0E, 0x93, 0x9A, 0x8F, 0x6A, 0xF1, 0x6F, 0x0A, 0x63 }
PBL_APP_INFO(MY_UUID,
             "Animation Crash", "Your Company",
             1, 0, /* App version */
             DEFAULT_MENU_ICON,
             APP_INFO_STANDARD_APP);

Window window;
TextLayer layer;
PropertyAnimation anim;

void handle_init(AppContextRef ctx) {
    window_init(&window, "Window Name");
	window_stack_push(&window, true /* Animated */);
	text_layer_init(&layer, GRect(10, 10, 100, 40));
	text_layer_set_text(&layer, "Animated layer");
	layer_add_child(window_get_root_layer(&window), (Layer*)&layer);
	property_animation_init_layer_frame(&anim, (Layer*)&layer, &GRect(10, 10, 100, 40), &GRect(10, 100, 100, 40));
	animation_set_duration(&anim.animation, 2000);
	animation_schedule(&anim.animation);
	animation_schedule(&anim.animation); // This line crashes.
}


void pbl_main(void *params) {
	PebbleAppHandlers handlers = {
		.init_handler = &handle_init
	};
	app_event_loop(params, &handlers);
}