show critical faults on the screen

src/error.h

@@ -2,8 +2,24 @@
 
 #include <Arduino.h>
 
-/// Error codes for critical error
-enum CriticalErrorCode { NoError, ErrTxWatchdog, ErrSleepEnterWait, ErrNoRadio, ErrUnspecified, UBloxInitFailed };
+/** Error codes for critical errors
+ * 
+ * The device might report these fault codes on the screen.  If you encounter a fault code, please
+ * post on the meshtastic.discourse.group and we'll try to help.
+ */
+enum CriticalErrorCode { 
+    NoError = 0, 
+    ErrTxWatchdog = 1, 
+    ErrSleepEnterWait = 2, 
+
+    // No Lora radio hardware could be found
+    ErrNoRadio = 3, 
+    ErrUnspecified = 4, 
+    ErrUBloxInitFailed = 5,
+
+    // This board was expected to have a power management chip and it is missing or broken
+    ErrNoAXP192 = 6 
+    };
 
 /// Record an error that should be reported via analytics
 void recordCriticalError(CriticalErrorCode code, uint32_t address = 0);