Lỗi error expected unqualified-id before if arduino là gì năm 2024

Arduino: 1.8.19 (Windows 10), Board: "ATmega48, No bootloader, EEPROM retained, 48 / 48A, BOD 2.7V, LTO enabled, External 16 MHz"

In file included from C:\Users\GL Music\Documents\Arduino\libraries\FreqCount\FreqCount.cpp:27:0:

C:\Users\GL Music\Documents\Arduino\libraries\FreqCount\FreqCount.cpp:87:3: error: 'counter_overflow_reset' was not declared in this scope