fatal error: stack overflow

runtime stack:
runtime.throw({0xd69a15?, 0x20?})
	GOROOT/src/runtime/panic.go:1077 +0x40 fp=0x40006bde00 sp=0x40006bddd0 pc=0x4a120
runtime.newstack()
	GOROOT/src/runtime/stack.go:1107 +0x458 fp=0x40006bdfb0 sp=0x40006bde00 pc=0x659f8
traceback: unexpected SPWRITE function runtime.morestack
runtime.morestack()
	src/runtime/asm_arm64.s:316 +0x70 fp=0x40006bdfb0 sp=0x40006bdfb0 pc=0x7f580