algo: Raise error if only one of output-file and output-type is specified.

Refs #3026

algo/base/Exceptions.h

@@ -5,18 +5,20 @@
 #define CBM_ALGO_BASE_EXCEPTIONS_H
 
 #include <exception>
+#include <string_view>
 
 #include <fmt/format.h>
 
 namespace cbm::algo
 {
   /**
-   * @brief Base class for exceptions
+   * @brief Base class for exceptions.
+   *
+   * @note Should not be thrown directly. Use one of the derived classes instead.
    */
-  class Exception : public std::runtime_error {
-  public:
+  struct Exception : std::runtime_error {
     template<typename... Args>
-    Exception(const char* fmt, Args&&... args) : std::runtime_error(fmt::format(fmt, std::forward<Args>(args)...))
+    Exception(std::string_view fmt, Args&&... args) : std::runtime_error(fmt::format(fmt, std::forward<Args>(args)...))
     {
     }
   };
@@ -24,7 +26,7 @@ namespace cbm::algo
   /**
    * @brief Indicates an unrecoverable error. Should tear down the process.
    */
-  class FatalError : public Exception {
+  struct FatalError : Exception {
     using Exception::Exception;
   };
 
@@ -32,7 +34,7 @@ namespace cbm::algo
    * Indicates an error during timeslice processing. Timeslice will be discarded.
    * Processing can continue with new timeslice.
    */
-  class ProcessingError : public Exception {
+  struct ProcessingError : Exception {
     using Exception::Exception;
   };