#49 Capture embedded zcashd errors

src/connection.cpp

@@ -221,9 +221,16 @@ bool ConnectionLoader::startEmbeddedZcashd() {
     if (!Settings::getInstance()->useEmbedded()) 
         return false;
 
+    // Static because it needs to survice even after this method returns.
+    static QString processStdErrOutput;
+
     if (ezcashd != nullptr) {
         if (ezcashd->state() == QProcess::NotRunning) {
             qDebug() << "Process started and then crashed";
+            if (!processStdErrOutput.isEmpty()) {
+                QMessageBox::critical(main, "zcashd error", "zcashd said: " + processStdErrOutput, 
+                                      QMessageBox::Ok);
+            }
             return false;
         } else {
             return true;
@@ -262,6 +269,12 @@ bool ConnectionLoader::startEmbeddedZcashd() {
         //qDebug() << "Couldn't start zcashd: " << error;
     });
 
+    QObject::connect(ezcashd, &QProcess::readyReadStandardError, [=]() {
+        auto output = ezcashd->readAllStandardError();
+        qDebug() << "zcashd stderr:" << output;
+        processStdErrOutput.append(output);
+    });
+
 #ifdef Q_OS_LINUX
     ezcashd->start(zcashdProgram);
 #elif defined(Q_OS_DARWIN)