Fix crash bugs on disconnect

Adds a nullptr check in the error recovery code that prevents crashes on disconnect.
Also prevents the use of an uninitialized pointer in the same code by tweaking the
connect bug fix from the previous commit.

Author: Alrik Vidstrom

src/USBHost/USBHost.cpp

@@ -697,16 +697,8 @@ bool USBHost::addEndpoint(USBDeviceConnected * dev, uint8_t intf_nb, USBEndpoint
         default:
             return false;
     }
-#else
-    // The code that follows this check shouldn't be executed for a control endpoint
-    if (CONTROL_ENDPOINT == (ep->getType()))
-    {
-        return true;
-    }
 #endif
     ep->dev = dev;
-    // This check might not be necessary when the control endpoint check is added above, but
-    // is included just in case
     if (nullptr != dev)
     {
         dev->addEndpoint(intf_nb, ep);

src/targets/TARGET_STM/USBEndpoint_STM.cpp

@@ -146,13 +146,17 @@ void USBEndpoint::setState(USB_TYPE st)
         /* small speed device with hub not supported
            if (this->speed) hcd_speed = HCD_SPEED_LOW;*/
 
-        // Notice that dev->getAddress() must be used instead of device_address, because the latter will contain
-        // incorrect values in certain cases
-        HAL_HCD_HC_Init((HCD_HandleTypeDef *)hced->hhcd, hced->ch_num, address, dev->getAddress(), hcd_speed,  type, size);
-        // HAL_HCD_HC_Init() doesn't fully enable the channel after disable above, so we do it here -->
-        USBx_HC(hced->ch_num)->HCCHAR &= ~USB_OTG_HCCHAR_CHDIS;
-        USBx_HC(hced->ch_num)->HCCHAR |= USB_OTG_HCCHAR_CHENA;
-        // <--
+        // If the device seems to be gone, there is no use trying to enable the channel again
+        if (nullptr != dev)
+        {
+            // Notice that dev->getAddress() must be used instead of device_address, because the latter will contain
+            // incorrect values in certain cases
+            HAL_HCD_HC_Init((HCD_HandleTypeDef *)hced->hhcd, hced->ch_num, address, dev->getAddress(), hcd_speed,  type, size);
+            // HAL_HCD_HC_Init() doesn't fully enable the channel after disable above, so we do it here -->
+            USBx_HC(hced->ch_num)->HCCHAR &= ~USB_OTG_HCCHAR_CHDIS;
+            USBx_HC(hced->ch_num)->HCCHAR |= USB_OTG_HCCHAR_CHENA;
+            // <--
+        }
     }
 }