if (NS_FAILED(rv) || pPref == nsnull)
if (NS_FAILED(rv) || !pPref)
static void DIR_ClearBoolPref (const char *pref){    nsresult rv = NS_OK;    NS_WITH_SERVICE(nsIPref, pPref, kPrefCID, &rv);     if (NS_FAILED(rv) || pPref == nsnull) 		return;	PRBool oldDefault;	PRInt32 prefErr = pPref->GetDefaultBoolPref (pref, &oldDefault);	DIR_ClearPrefBranch (pref);	if (prefErr >= 0)		pPref->SetDefaultBoolPref (pref, oldDefault);}