Ok, so you have this…
Fatal exception (28):
epc1=0x40245f15, epc2=0x00000000, epc3=0x401012b6, excvaddr=0x00000004, depc=0x00000000
ets Jan 8 2013,rst cause:1, boot mode:(1,3)
ets Jan 8 2013,rst cause:4, boot mode:(1,3)
If you want to find the origin of your problem, you can disassemble the .out elf file that has been produced during compilation. To do it, just type:
C:\ESP8266\ESP8266windev\xtensa-lx106-elf\bin\xtensa-lx106-elf-objdump.exe -d esp8266_at.out >disassemble.txt
Now find 40245f15 and you will see where the error appears.