🎨 Misc. fixes, cleanup

Co-Authored-By: Martin Turski <turningtides@outlook.de>

Marlin/Marlin.ino

@@ -27,7 +27,7 @@ Configuration
   - https://github.com/MarlinFirmware/Configurations
     Example configurations for several printer models.
 
-  - https://www.youtube.com/watch?v=3gwWVFtdg-4
+  - https://youtu.be/3gwWVFtdg-4
     A good 20-minute overview of Marlin configuration by Tom Sanladerer.
     (Applies to Marlin 1.0.x, so Jerk and Acceleration should be halved.)
     Also... https://www.google.com/search?tbs=vid%3A1&q=configure+marlin

Marlin/src/HAL/ESP32/ota.cpp

@@ -50,7 +50,7 @@ void OTA_init() {
     })
     .onError([](ota_error_t error) {
       Serial.printf("Error[%u]: ", error);
-      char *str;
+      const char *str = "unknown";
       switch (error) {
         case OTA_AUTH_ERROR:    str = "Auth Failed";    break;
         case OTA_BEGIN_ERROR:   str = "Begin Failed";   break;

Marlin/src/core/serial_base.h

@@ -23,6 +23,8 @@
 
 #include "../inc/MarlinConfigPre.h"
 
+#include <stddef.h> // for size_t
+
 #if ENABLED(EMERGENCY_PARSER)
   #include "../feature/e_parser.h"
 #endif

Marlin/src/lcd/tft_io/tft_orientation.h

@@ -82,4 +82,3 @@
 #ifndef TOUCH_ORIENTATION
   #define TOUCH_ORIENTATION     TOUCH_LANDSCAPE
 #endif
-

Marlin/src/libs/numtostr.cpp

@@ -28,7 +28,7 @@
 char conv[9] = { 0 };
 
 #define DIGIT(n) ('0' + (n))
-#define DIGIMOD(n, f) DIGIT((n)/(f) % 10)
+#define DIGIMOD(n, f) DIGIT(((n)/(f)) % 10)
 #define RJDIGIT(n, f) ((n) >= (f) ? DIGIMOD(n, f) : ' ')
 #define MINUSOR(n, alt) (n >= 0 ? (alt) : (n = -n, '-'))
 #define INTFLOAT(V,N) (((V) * 10 * pow(10, N) + ((V) < 0 ? -5: 5)) / 10)      // pow10?