Fixed some more or less valid clang and clang-tidy errors.

source/mijin/io/stream.cpp

@@ -169,6 +169,9 @@ StreamError FileStream::seek(std::intptr_t pos, SeekMode seekMode)
         case SeekMode::RELATIVE_TO_END:
             origin = SEEK_END;
             break;
+        default:
+            assert(!"Invalid value passed as seekMode!");
+            return StreamError::UNKNOWN_ERROR;
     }
     const int result = std::fseek(handle, static_cast<long>(pos), origin);
     if (result != 0 || std::ferror(handle)) {

source/mijin/util/scope_guard.hpp

@@ -7,7 +7,7 @@
 #include "./common_macros.hpp"
 
 #define MIJIN_SCOPE_EXIT_NAMED(name) \
-mijin::ScopeExitGuard name = [&]()
+const mijin::ScopeExitGuard name = [&]()
 
 #define MIJIN_SCOPE_EXIT MIJIN_SCOPE_EXIT_NAMED(MIJIN_CONCAT(MIJIN_CONCAT(scope_guard_, __LINE__), __))
 
@@ -16,7 +16,7 @@ namespace mijin
 class ScopeExitGuard
 {
 private:
-    std::function<void(void)> func;
+    mutable std::function<void(void)> func; // variable is declared const to make clang-tidy happy, but we still want to be able to reset()
 public:
     template<typename TFunc>
     inline ScopeExitGuard(TFunc&& func_) noexcept : func(std::forward<TFunc>(func_)) {}
@@ -32,7 +32,7 @@ public:
     ScopeExitGuard& operator=(const ScopeExitGuard&) noexcept = delete;
     ScopeExitGuard& operator=(ScopeExitGuard&&) noexcept = delete;
 
-    inline void reset() noexcept
+    inline void reset() const noexcept
     {
         func = {};
     }