Arduino “warning: internal error: out of range error”

There are probably a million other reasons you could get this error, but I didn’t see anyone document the case I got it: I wrote some raw assembly (i.e., hexadecimal machine code) and got the instruction length wrong. I.e., something like this:

__asm volatile(
    ".byte 0x00 \n"
);

Well, AVR instructions are 16 bits, so clearly the one-byte thing above wouldn’t encode a valid instruction and would ruin alignment, so it would have to look at this:

__asm volatile(
    ".byte 0x00 \n"
    ".byte 0x00 \n"
);