Prevent access to invalid pointer
Prevent access to invalid pointer

The commit added check to make sure no invalid memory access even when
the decoder instance is never initialized.

Change-Id: I4da343d0b3c78c27777ac7f5ce7688562c69f0c5

jacklicn/webm.libvpx,thdav/aom,stewnorriss/libvpx,Laknot/libvpx,reimaginemedia/webm.libvpx,charup/https---github.com-webmproject-libvpx-,sanyaade-teachings/libvpx,shacklettbp/aom,stewnorriss/libvpx,running770/libvpx,mwgoldsmith/libvpx,altogother/webm.libvpx,turbulenz/libvpx,pcwalton/libvpx,jdm/libvpx,abwiz0086/webm.libvpx,mwgoldsmith/vpx,smarter/aom,gshORTON/webm.libvpx,openpeer/libvpx_new,kleopatra999/webm.libvpx,openpeer/libvpx_new,matanbs/vp982,sanyaade-teachings/libvpx,Laknot/libvpx,Acidburn0zzz/webm.libvpx,kim42083/webm.libvpx,mwgoldsmith/vpx,altogother/webm.libvpx,jdm/libvpx,VTCSecureLLC/libvpx,smarter/aom,jmvalin/aom,pcwalton/libvpx,mwgoldsmith/vpx,smarter/aom,mbebenita/aom,mwgoldsmith/libvpx,abwiz0086/webm.libvpx,lyx2014/libvpx_c,ittiamvpx/libvpx,iniwf/webm.libvpx,shareefalis/libvpx,kim42083/webm.libvpx,jdm/libvpx,kim42083/webm.libvpx,shareefalis/libvpx,Laknot/libvpx,matanbs/vp982,Distrotech/libvpx,gshORTON/webm.libvpx,kalli123/webm.libvpx,shareefalis/libvpx,shacklettbp/aom,ittiamvpx/libvpx-1,shyamalschandra/libvpx,lyx2014/libvpx_c,webmproject/libvpx,Maria1099/webm.libvpx,ittiamvpx/libvpx,Topopiccione/libvpx,ittiamvpx/libvpx,jacklicn/webm.libvpx,WebRTC-Labs/libvpx,Maria1099/webm.libvpx,lyx2014/libvpx_c,n4t/libvpx,mbebenita/aom,pcwalton/libvpx,iniwf/webm.libvpx,jacklicn/webm.libvpx,mwgoldsmith/vpx,liqianggao/libvpx,altogother/webm.libvpx,shyamalschandra/libvpx,mbebenita/aom,Topopiccione/libvpx,Suvarna1488/webm.libvpx,running770/libvpx,jacklicn/webm.libvpx,kim42083/webm.libvpx,shacklettbp/aom,running770/libvpx,webmproject/libvpx,altogother/webm.libvpx,matanbs/webm.libvpx,gshORTON/webm.libvpx,Acidburn0zzz/webm.libvpx,smarter/aom,altogother/webm.libvpx,kleopatra999/webm.libvpx,openpeer/libvpx_new,thdav/aom,iniwf/webm.libvpx,running770/libvpx,Maria1099/webm.libvpx,openpeer/libvpx_new,charup/https---github.com-webmproject-libvpx-,zofuthan/libvpx,GrokImageCompression/aom,Suvarna1488/webm.libvpx,running770/libvpx,reimaginemedia/webm.libvpx,goodleixiao/vpx,stewnorriss/libvpx,hsueceumd/test_hui,matanbs/webm.libvpx,mwgoldsmith/vpx,shacklettbp/aom,zofuthan/libvpx,ittiamvpx/libvpx-1,turbulenz/libvpx,lyx2014/libvpx_c,luctrudeau/aom,stewnorriss/libvpx,VTCSecureLLC/libvpx,ittiamvpx/libvpx,gshORTON/webm.libvpx,kalli123/webm.libvpx,charup/https---github.com-webmproject-libvpx-,pcwalton/libvpx,charup/https---github.com-webmproject-libvpx-,jmvalin/aom,goodleixiao/vpx,liqianggao/libvpx,matanbs/vp982,mwgoldsmith/libvpx,thdav/aom,kim42083/webm.libvpx,kleopatra999/webm.libvpx,sanyaade-teachings/libvpx,lyx2014/libvpx_c,kalli123/webm.libvpx,jacklicn/webm.libvpx,VTCSecureLLC/libvpx,Laknot/libvpx,matanbs/vp982,mbebenita/aom,shyamalschandra/libvpx,pcwalton/libvpx,GrokImageCompression/aom,abwiz0086/webm.libvpx,matanbs/webm.libvpx,kleopatra999/webm.libvpx,Acidburn0zzz/webm.libvpx,felipebetancur/libvpx,turbulenz/libvpx,shacklettbp/aom,mwgoldsmith/libvpx,turbulenz/libvpx,sanyaade-teachings/libvpx,mbebenita/aom,kim42083/webm.libvpx,kleopatra999/webm.libvpx,Suvarna1488/webm.libvpx,hsueceumd/test_hui,VTCSecureLLC/libvpx,goodleixiao/vpx,webmproject/libvpx,ittiamvpx/libvpx,ShiftMediaProject/libvpx,Distrotech/libvpx,jdm/libvpx,openpeer/libvpx_new,Acidburn0zzz/webm.libvpx,Topopiccione/libvpx,goodleixiao/vpx,turbulenz/libvpx,Distrotech/libvpx,Distrotech/libvpx,liqianggao/libvpx,matanbs/webm.libvpx,shyamalschandra/libvpx,shareefalis/libvpx,luctrudeau/aom,shareefalis/libvpx,n4t/libvpx,sanyaade-teachings/libvpx,iniwf/webm.libvpx,Suvarna1488/webm.libvpx,zofuthan/libvpx,luctrudeau/aom,kleopatra999/webm.libvpx,turbulenz/libvpx,ittiamvpx/libvpx-1,reimaginemedia/webm.libvpx,iniwf/webm.libvpx,felipebetancur/libvpx,shyamalschandra/libvpx,jmvalin/aom,Maria1099/webm.libvpx,hsueceumd/test_hui,webmproject/libvpx,thdav/aom,reimaginemedia/webm.libvpx,shacklettbp/aom,matanbs/vp982,mbebenita/aom,kalli123/webm.libvpx,n4t/libvpx,liqianggao/libvpx,felipebetancur/libvpx,lyx2014/libvpx_c,ShiftMediaProject/libvpx,VTCSecureLLC/libvpx,zofuthan/libvpx,altogother/webm.libvpx,mwgoldsmith/libvpx,jmvalin/aom,jdm/libvpx,WebRTC-Labs/libvpx,Suvarna1488/webm.libvpx,jacklicn/webm.libvpx,turbulenz/libvpx,Maria1099/webm.libvpx,jdm/libvpx,ittiamvpx/libvpx-1,matanbs/vp982,stewnorriss/libvpx,reimaginemedia/webm.libvpx,webmproject/libvpx,GrokImageCompression/aom,Suvarna1488/webm.libvpx,mbebenita/aom,Topopiccione/libvpx,thdav/aom,liqianggao/libvpx,VTCSecureLLC/libvpx,matanbs/webm.libvpx,WebRTC-Labs/libvpx,ittiamvpx/libvpx,n4t/libvpx,matanbs/vp982,gshORTON/webm.libvpx,luctrudeau/aom,felipebetancur/libvpx,ShiftMediaProject/libvpx,Topopiccione/libvpx,mwgoldsmith/libvpx,luctrudeau/aom,goodleixiao/vpx,ittiamvpx/libvpx-1,GrokImageCompression/aom,reimaginemedia/webm.libvpx,goodleixiao/vpx,turbulenz/libvpx,matanbs/webm.libvpx,shareefalis/libvpx,hsueceumd/test_hui,openpeer/libvpx_new,abwiz0086/webm.libvpx,stewnorriss/libvpx,Distrotech/libvpx,Acidburn0zzz/webm.libvpx,GrokImageCompression/aom,WebRTC-Labs/libvpx,abwiz0086/webm.libvpx,WebRTC-Labs/libvpx,ShiftMediaProject/libvpx,luctrudeau/aom,Laknot/libvpx,Topopiccione/libvpx,mwgoldsmith/vpx,smarter/aom,iniwf/webm.libvpx,shyamalschandra/libvpx,felipebetancur/libvpx,Maria1099/webm.libvpx,hsueceumd/test_hui,running770/libvpx,jmvalin/aom,turbulenz/libvpx,Distrotech/libvpx,charup/https---github.com-webmproject-libvpx-,smarter/aom,ittiamvpx/libvpx-1,charup/https---github.com-webmproject-libvpx-,hsueceumd/test_hui,n4t/libvpx,jmvalin/aom,Laknot/libvpx,kalli123/webm.libvpx,zofuthan/libvpx,felipebetancur/libvpx,webmproject/libvpx,GrokImageCompression/aom,abwiz0086/webm.libvpx,liqianggao/libvpx,mbebenita/aom,kalli123/webm.libvpx,Acidburn0zzz/webm.libvpx,gshORTON/webm.libvpx,zofuthan/libvpx,thdav/aom,ShiftMediaProject/libvpx,pcwalton/libvpx,mbebenita/aom