esp32/main: Check if main GC heap allocation failed.

If the heap allocation fails we will crash if we continue, so at least we
can show a clear error message so one can figure out memory allocation was
the problem (instead of just seeing some arbitrary null pointer error
later).

Signed-off-by: Daniël van de Giessen <daniel@dvdgiessen.nl>

ports/esp32/main.c

@@ -116,6 +116,10 @@ void mp_task(void *pvParameter) {
     }
 
     void *mp_task_heap = MP_PLAT_ALLOC_HEAP(MICROPY_GC_INITIAL_HEAP_SIZE);
+    if (mp_task_heap == NULL) {
+        printf("mp_task_heap allocation failed!\n");
+        esp_restart();
+    }
 
 soft_reset:
     // initialise the stack pointer for the main thread