Merged revision(s) 20193 from trunk/OpenMPT:

[Fix] mpt/library/library.hpp: When loading a library on Windows, do not return std::optional{NULL} if loading failed, but return std::nullopt instead. Otherwise, the code later gets confused as it finds a HANDLE (which is NULL) and assumes the library was loaded successfully. Non-Windows platforms were not affected. Fixes <https://bugs.openmpt.org/view.php?id=1749>.
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git-svn-id: https://source.openmpt.org/svn/openmpt/branches/OpenMPT-1.31@20194 56274372-70c3-4bfc-bfc3-4c3a0b034d27

src/mpt/library/library.hpp

@@ -304,6 +304,10 @@ class library {
 
 #endif // MPT_OS_WINDOWS_WINRT
 
+		if (!hModule) {
+			return std::nullopt;
+		}
+
 		return library{hModule};
 	}