avifil32: AVIFileGetStream should set stream to NULL in case of an error.

dlls/avifil32/avifile.c

@@ -316,6 +316,7 @@ static HRESULT WINAPI IAVIFile_fnGetStream(IAVIFile *iface, IAVIStream **avis, D
   }
 
   /* Sorry, but the specified stream doesn't exist */
+  *avis = NULL;
   return AVIERR_NODATA;
 }
 

dlls/avifil32/tests/api.c

@@ -373,6 +373,11 @@ static void test_default_data(void)
     res = AVIFileOpenA(&pFile, filename, OF_SHARE_DENY_WRITE, 0L);
     ok(res == 0, "Unable to open file: error=%u\n", res);
 
+    pStream0 = (void *)0xdeadbeef;
+    res = AVIFileGetStream(pFile, &pStream0, ~0U, 0);
+    ok(res == AVIERR_NODATA, "expected AVIERR_NODATA, got %u\n", res);
+    ok(pStream0 == NULL, "AVIFileGetStream should set stream to NULL\n");
+
     res = AVIFileGetStream(pFile, &pStream0, 0, 0);
     ok(res == 0, "Unable to open video stream: error=%u\n", res);