logid: Fail on invalid Configurations

NixOS will soon have a runtime test for logiops which uses an
invalid configuration as a baseline, expecting it to fail.

Silent errors are not nice for users; systemd does not inform users
of stderr messages in nominally running services.

NixOS/nixpkgs#167388

src/logid/Configuration.cpp

@@ -34,11 +34,11 @@ Configuration::Configuration(const std::string& config_file)
     } catch(const FileIOException &e) {
         logPrintf(ERROR, "I/O Error while reading %s: %s", config_file.c_str(),
                 e.what());
-        throw e;
+        exit(EXIT_FAILURE);
     } catch(const ParseException &e) {
         logPrintf(ERROR, "Parse error in %s, line %d: %s", e.getFile(),
                 e.getLine(), e.getError());
-        throw e;
+        exit(EXIT_FAILURE);
     }
 
     const Setting &root = _config.getRoot();

src/logid/logid.cpp

@@ -168,7 +168,8 @@ int main(int argc, char** argv)
         global_config = std::make_shared<Configuration>(options.config_file);
     }
     catch (std::exception &e) {
-        global_config = std::make_shared<Configuration>();
+        logPrintf(ERROR, "%s", e.what());
+        return EXIT_FAILURE;
     }
     global_workqueue = std::make_shared<workqueue>(
             global_config->workerCount());