fatal error: unknown caller pc runtime stack: runtime.throw(0x133bd5f, 0x11) GOROOT/src/runtime/panic.go:1117 +0x72 fp=0xc00060fc30 sp=0xc00060fc00 pc=0x438072 runtime.gentraceback(0x435cbb, 0xc000af7a80, 0x0, 0xc00354f080, 0x0, 0x0, 0x7fffffff, 0xc00060ffa8, 0x0, 0x0, ...) GOROOT/src/runtime/traceback.go:261 +0x1a56 fp=0xc00060ff50 sp=0xc00060fc30 pc=0x460a56 runtime.addOneOpenDeferFrame.func1() GOROOT/src/runtime/panic.go:717 +0x91 fp=0xc00060ffd0 sp=0xc00060ff50 pc=0x469591 runtime.systemstack(0x0) src/runtime/asm_amd64.s:379 +0x66 fp=0xc00060ffd8 sp=0xc00060ffd0 pc=0x470ba6 runtime.mstart() GOROOT/src/runtime/proc.go:1246 fp=0xc00060ffe0 sp=0xc00060ffd8 pc=0x43d340