give error if both unicode/map are enabled

quantum/quantum_keycodes.h

@@ -45,6 +45,9 @@ enum quantum_keycodes {
     QK_LAYER_TAP_TOGGLE_MAX = 0x58FF,
     QK_MOD_TAP            = 0x6000,
     QK_MOD_TAP_MAX        = 0x7FFF,
+#if defined(UNICODEMAP_ENABLE) && defined(UNICODE_ENABLE)
+    #error "Cannot enable both UNICODEMAP && UNICODE"
+#endif
 #ifdef UNICODE_ENABLE
     QK_UNICODE            = 0x8000,
     QK_UNICODE_MAX        = 0xFFFF,