qt: Add BitcoinApplication::handleNonFatalException function

This helper function will be used in the following commits.

Co-authored-by: Russell Yanofsky <russ@yanofsky.org>

src/qt/bitcoin.cpp

@@ -426,6 +426,16 @@ void BitcoinApplication::handleRunawayException(const QString &message)
     ::exit(EXIT_FAILURE);
 }
 
+void BitcoinApplication::handleNonFatalException(const QString& message)
+{
+    assert(QThread::currentThread() == thread());
+    QMessageBox::warning(
+        nullptr, tr("Internal error"),
+        tr("An internal error occurred. %1 will attempt to continue safely. This is "
+           "an unexpected bug which can be reported as described below.").arg(PACKAGE_NAME) %
+        QLatin1String("<br><br>") % GUIUtil::MakeHtmlLink(message, PACKAGE_BUGREPORT));
+}
+
 WId BitcoinApplication::getMainWinId() const
 {
     if (!window)

src/qt/bitcoin.h

@@ -99,6 +99,12 @@ public Q_SLOTS:
     /// Handle runaway exceptions. Shows a message box with the problem and quits the program.
     void handleRunawayException(const QString &message);
 
+    /**
+     * A helper function that shows a message box
+     * with details about a non-fatal exception.
+     */
+    void handleNonFatalException(const QString& message);
+
 Q_SIGNALS:
     void requestedInitialize();
     void requestedShutdown();