Laser Coolant Flow Meter / Safety Shutdown (#21431)

Co-authored-by: Scott Lahteine <thinkyhead@users.noreply.github.com>

Marlin/src/gcode/gcode.cpp

@@ -57,6 +57,10 @@ GcodeSuite gcode;
   #include "../feature/spindle_laser.h"
 #endif
 
+#if ENABLED(FLOWMETER_SAFETY)
+  #include "../feature/cooler.h"
+#endif
+
 #if ENABLED(PASSWORD_FEATURE)
   #include "../feature/password/password.h"
 #endif
@@ -278,6 +282,13 @@ void GcodeSuite::process_parsed_command(const bool no_ok/*=false*/) {
     }
   #endif
 
+  #if ENABLED(FLOWMETER_SAFETY)
+    if (cooler.fault) {
+      SERIAL_ECHO_MSG(STR_FLOWMETER_FAULT);
+      return;
+    }
+  #endif
+
   // Handle a known G, M, or T
   switch (parser.command_letter) {
     case 'G': switch (parser.codenum) {