Prevent coredump in SD which should not call getmininginfo

src/rpc.cpp

@@ -856,6 +856,7 @@ void RPC::getInfoThenRefresh(bool force) {
         // Get mining info
         // This is better+faster than calling multiple RPCs such as getlocalsolps/getnetworksolps/getgenerate
         // and getlocalsolps returns non-zero values even when not mining, which is not what we want
+        if(isdragonx) {
         conn->doRPCIgnoreError(makePayload("getmininginfo"), [=](const QJsonValue& reply) {
             QString localhashps   = QString::number( reply["localhashps"].toDouble() );
             QString networkhashps = QString::number( reply["networkhashps"].toDouble() );
@@ -869,6 +870,13 @@ void RPC::getInfoThenRefresh(bool force) {
 
             auto stopbutton  = ui->tabWidget->findChild<QPushButton *>("stopmining");
             auto startbutton = ui->tabWidget->findChild<QPushButton *>("startmining");
+            if (stopbutton == nullptr) {
+                return;
+            }
+            if (startbutton == nullptr) {
+                return;
+            }
+
             if(generate == "1") {
                 // already mining
                 stopbutton->setEnabled(true);
@@ -945,6 +953,7 @@ void RPC::getInfoThenRefresh(bool force) {
             }
 
         });
+        }
 
         // Get network info
         conn->doRPCIgnoreError(makePayload("getnetworkinfo"), [=](const QJsonValue& reply) {