IO: changed FileMode::SysRead to use the virtual fs paths as fallback…

…, too

this fixes an issue where the downloaded files from the asset panel couldn't
get opened because the file system archive instance is expecting a full path
at that point

src/modules/io/File.h

@@ -20,7 +20,7 @@ enum class FileMode {
 	Read,		/**< reading from the virtual file system */
 	Write,		/**< writing into the virtual file system */
 	Append,		/**< appending to an existing file or create a new one */
-	SysRead,	/**< reading from the given path */
+	SysRead,	/**< reading from the given path - using virtual paths as fallback */
 	SysWrite,	/**< writing into the given path */
 	ReadNoHome	/**< reading from the virtual file system but skip user setting files in the home directories */
 };

src/modules/io/Filesystem.cpp

@@ -395,7 +395,7 @@ io::FilePtr Filesystem::open(const core::String &filename, FileMode mode) const
 	if (mode == FileMode::SysWrite) {
 		Log::debug("Use absolute path to open file %s for writing", filename.c_str());
 		return core::make_shared<io::File>(filename, mode);
-	} else if (mode == FileMode::SysRead) {
+	} else if (mode == FileMode::SysRead && fs_exists(filename.c_str())) {
 		return core::make_shared<io::File>(filename, mode);
 	} else if (mode == FileMode::Write) {
 		if (!isRelativePath(filename)) {