What were you doing to cause the error? You haven't provided any details to help diagnose your issue.
I'll assume, in the absence of any information, that you were trying to build Lazarus in which case try:
make LCL_PLATFORM=cocoa CPU_TARGET=x86_64 bigide
If you're building Lazarus from within the IDE:
* In Project > Project Options: "Config and Target" section set the "Target CPU family" to be "x86_64"
* In Project > Project Options: "Additions and Overrides" section click on the "Set LCLWidgetType" pulldown and set the value to "Cocoa".
If that's not your problem, then you're going to have to tell us what you were doing to cause the error, although it is probably related to the settings outlined above.