Add basic error handling.

src/main.cpp

@@ -17,13 +17,19 @@
 #include "options.hpp"
 
 #include <boost/locale/generator.hpp>
+#include <boost/program_options/errors.hpp>
+#include <boost/program_options/variables_map.hpp>
 
 #include <cstdlib>
+#include <exception>
 #include <iostream>
 #include <locale>
 
 int main(int argc, char *argv[])
 {
+    namespace po = boost::program_options;
+
+    using std::cerr;
     using std::cout;
 
     boost::locale::generator locale_generator;
@@ -33,7 +39,16 @@ int main(int argc, char *argv[])
     std::locale::global(locale_generator(""));
     cout.imbue(std::locale());
 
-    auto vm{epubgrep::parse_options(argc, argv)};
+    po::variables_map vm;
+    try
+    {
+        vm = epubgrep::parse_options(argc, argv);
+    }
+    catch (std::exception &e)
+    { // Exceptions we can't recover from or ones we don't know.
+        cerr << "ERROR: " << e.what() << '\n';
+        return EXIT_FAILURE;
+    }
 
     if (vm.count("help") + vm.count("version") > 0)
     {