qcap: Make sure input to AMStreamConfig_SetFormat is not NULL.

dlls/qcap/vfwcapture.c

@@ -400,7 +400,7 @@ AMStreamConfig_SetFormat(IAMStreamConfig *iface, AM_MEDIA_TYPE *pmt)
     ICOM_THIS_MULTI(VfwCapture, IAMStreamConfig_vtbl, iface);
     IPinImpl *pin;
 
-    TRACE("(%p): %p->%p\n", iface, pmt, pmt->pbFormat);
+    TRACE("(%p): %p->%p\n", iface, pmt, pmt ? pmt->pbFormat : NULL);
 
     if (This->state != State_Stopped)
     {
@@ -408,6 +408,12 @@ AMStreamConfig_SetFormat(IAMStreamConfig *iface, AM_MEDIA_TYPE *pmt)
         return VFW_E_NOT_STOPPED;
     }
 
+    if (!pmt)
+    {
+        TRACE("pmt is NULL\n");
+        return E_POINTER;
+    }
+
     dump_AM_MEDIA_TYPE(pmt);
 
     pin = (IPinImpl *)This->pOutputPin;