Fix reset pin null reference, construct error null reference

Author: hierophect

shared-module/displayio/FourWire.c

@@ -76,7 +76,9 @@ void common_hal_displayio_fourwire_deinit(displayio_fourwire_obj_t* self) {
 
     common_hal_reset_pin(self->command.pin);
     common_hal_reset_pin(self->chip_select.pin);
-    common_hal_reset_pin(self->reset.pin);
+    if (self->reset.pin) {
+        common_hal_reset_pin(self->reset.pin);
+    }
 }
 
 bool common_hal_displayio_fourwire_reset(mp_obj_t obj) {

shared-module/displayio/I2CDisplay.c

@@ -53,6 +53,7 @@ void common_hal_displayio_i2cdisplay_construct(displayio_i2cdisplay_obj_t* self,
 
     // Probe the bus to see if a device acknowledges the given address.
     if (!common_hal_busio_i2c_probe(i2c, device_address)) {
+        self->base.type = &mp_type_NoneType;
         mp_raise_ValueError_varg(translate("Unable to find I2C Display at %x"), device_address);
     }
 
@@ -71,7 +72,9 @@ void common_hal_displayio_i2cdisplay_deinit(displayio_i2cdisplay_obj_t* self) {
         common_hal_busio_i2c_deinit(self->bus);
     }
 
-    common_hal_reset_pin(self->reset.pin);
+    if (self->reset.pin) {
+        common_hal_reset_pin(self->reset.pin);
+    }
 }
 
 bool common_hal_displayio_i2cdisplay_reset(mp_obj_t obj) {