Assisted Tramming requires a probe (#18912)

Marlin/Configuration_adv.h

 #endif
 
 //
-// Add the G35 command to read bed corners to help adjust screws.
+// Add the G35 command to read bed corners to help adjust screws. Requires a bed probe.
 //
 //#define ASSISTED_TRAMMING
 #if ENABLED(ASSISTED_TRAMMING)

Marlin/src/inc/SanityCheck.h

 #endif
 
 /**
+ * G35 Assisted Tramming
+ */
+#if ENABLED(ASSISTED_TRAMMING) && !HAS_BED_PROBE
+  #error "ASSISTED_TRAMMING requires a bed probe."
+#endif
+
+/**
  * G38 Probe Target
  */
 #if ENABLED(G38_PROBE_TARGET)