Bug 1732549 - fix Crash using newsgroup after View > Threads > Unread. r=benc

Differential Revision: https://phabricator.services.mozilla.com/D126638

--HG--
extra : rebase_source : ea9fc7df3c32e2711ea81cbfa3d91aa72d6d9a18

mailnews/base/src/nsMsgGroupThread.cpp

@@ -604,14 +604,12 @@ nsresult nsMsgGroupThread::GetChildHdrForKey(nsMsgKey desiredKey,
 NS_IMETHODIMP nsMsgGroupThread::GetFirstUnreadChild(nsIMsgDBHdr** result) {
   NS_ENSURE_ARG_POINTER(result);
 
-  nsresult rv = NS_OK;
-
   uint32_t numChildren = 0;
   GetNumChildren(&numChildren);
 
   for (uint32_t childIndex = 0; childIndex < numChildren; childIndex++) {
     nsCOMPtr<nsIMsgDBHdr> child;
-    rv = GetChildHdrAt(childIndex, getter_AddRefs(child));
+    nsresult rv = GetChildHdrAt(childIndex, getter_AddRefs(child));
     if (NS_SUCCEEDED(rv) && child) {
       nsMsgKey msgKey;
       child->GetMessageKey(&msgKey);
@@ -625,7 +623,7 @@ NS_IMETHODIMP nsMsgGroupThread::GetFirstUnreadChild(nsIMsgDBHdr** result) {
     }
   }
 
-  return rv;
+  return (*result) ? NS_OK : NS_ERROR_NULL_POINTER;
 }
 
 NS_IMETHODIMP nsMsgGroupThread::GetNewestMsgDate(uint32_t* aResult) {

mailnews/base/src/nsMsgXFViewThread.cpp

@@ -412,15 +412,13 @@ NS_IMETHODIMP
 nsMsgXFViewThread::GetFirstUnreadChild(nsIMsgDBHdr** aResult) {
   NS_ENSURE_ARG(aResult);
   uint32_t numChildren;
-  nsresult rv = NS_OK;
-
   GetNumChildren(&numChildren);
 
   if ((int32_t)numChildren < 0) numChildren = 0;
 
   for (uint32_t childIndex = 0; childIndex < numChildren; childIndex++) {
     nsCOMPtr<nsIMsgDBHdr> child;
-    rv = GetChildHdrAt(childIndex, getter_AddRefs(child));
+    nsresult rv = GetChildHdrAt(childIndex, getter_AddRefs(child));
     if (NS_SUCCEEDED(rv) && child) {
       nsMsgKey msgKey;
       child->GetMessageKey(&msgKey);
@@ -437,7 +435,7 @@ nsMsgXFViewThread::GetFirstUnreadChild(nsIMsgDBHdr** aResult) {
     }
   }
 
-  return rv;
+  return (*aResult) ? NS_OK : NS_ERROR_NULL_POINTER;
 }
 
 NS_IMETHODIMP

mailnews/db/msgdb/src/nsMsgThread.cpp

@@ -978,7 +978,6 @@ nsresult nsMsgThread::GetChildHdrForKey(nsMsgKey desiredKey,
 NS_IMETHODIMP nsMsgThread::GetFirstUnreadChild(nsIMsgDBHdr** result) {
   NS_ENSURE_ARG_POINTER(result);
 
-  nsresult rv = NS_OK;
   uint8_t minLevel = 0xff;
 
   uint32_t numChildren = 0;
@@ -988,7 +987,7 @@ NS_IMETHODIMP nsMsgThread::GetFirstUnreadChild(nsIMsgDBHdr** result) {
 
   for (uint32_t childIndex = 0; childIndex < numChildren; childIndex++) {
     nsCOMPtr<nsIMsgDBHdr> child;
-    rv = GetChildHdrAt(childIndex, getter_AddRefs(child));
+    nsresult rv = GetChildHdrAt(childIndex, getter_AddRefs(child));
     if (NS_SUCCEEDED(rv) && child) {
       nsMsgKey msgKey;
       child->GetMessageKey(&msgKey);
@@ -1022,7 +1021,7 @@ NS_IMETHODIMP nsMsgThread::GetFirstUnreadChild(nsIMsgDBHdr** result) {
   }
 
   retHdr.forget(result);
-  return rv;
+  return (*result) ? NS_OK : NS_ERROR_NULL_POINTER;
 }
 
 NS_IMETHODIMP nsMsgThread::GetNewestMsgDate(uint32_t* aResult) {