Fix for unhandled error cases when using Media Foundation

Some function calls to Media Foundation can fail and retrun null
pointers. They should be checked before being dereferenced to avoid a
crash.

modules/videoio/src/cap_msmf.cpp

@@ -1986,13 +1986,17 @@ long videoDevice::resetDevice(IMFActivate *pActivate)
                 &vd_pFriendlyName,
                 NULL
                 );
+        if (SUCCEEDED(hr))
           hr = pActivate->ActivateObject(
               __uuidof(IMFMediaSource),
               (void**)&pSource
               );
+        if (SUCCEEDED(hr) && pSource)
+        {
           enumerateCaptureFormats(pSource);
           buildLibraryofTypes();
           SafeRelease(&pSource);
+        }//end if (SUCCEEDED(hr) && pSource)
         if(FAILED(hr))
         {
             vd_pFriendlyName = NULL;
@@ -2638,7 +2642,12 @@ HRESULT videoDevice::enumerateCaptureFormats(IMFMediaSource *pSource)
     _ComPtr<IMFStreamDescriptor> pSD = NULL;
     _ComPtr<IMFMediaTypeHandler> pHandler = NULL;
     _ComPtr<IMFMediaType> pType = NULL;
-    HRESULT hr = pSource->CreatePresentationDescriptor(pPD.GetAddressOf());
+    HRESULT hr = !pSource ? E_POINTER : S_OK;
+    if (FAILED(hr))
+    {
+        goto done;
+    }
+    hr = pSource->CreatePresentationDescriptor(pPD.GetAddressOf());
     if (FAILED(hr))
     {
         goto done;
@@ -3815,7 +3824,12 @@ HRESULT CvCaptureFile_MSMF::enumerateCaptureFormats(IMFMediaSource *pSource)
     _ComPtr<IMFStreamDescriptor> pSD = NULL;
     _ComPtr<IMFMediaTypeHandler> pHandler = NULL;
     _ComPtr<IMFMediaType> pType = NULL;
-    HRESULT hr = pSource->CreatePresentationDescriptor(pPD.GetAddressOf());
+    HRESULT hr = !pSource ? E_POINTER : S_OK;
+    if (FAILED(hr))
+    {
+        goto done;
+    }
+    hr = pSource->CreatePresentationDescriptor(pPD.GetAddressOf());
     if (FAILED(hr))
     {
         goto done;