Don't try to open IPS/UPS/BPS patches if they don't exist

patch.c

@@ -26,6 +26,7 @@
 #include <file/file_path.h>
 #include <file/file_archive.h>
 #include <retro_file.h>
+#include <retro_stat.h>
 #include <string/stdstring.h>
 
 #include "patch.h"
@@ -499,6 +500,8 @@ static bool apply_patch_content(uint8_t **buf,
    ssize_t ret_size         = *size;
    uint8_t *ret_buf         = *buf;
    
+   if (!path_is_valid(patch_path))
+      return false;
    if (!retro_read_file(patch_path, &patch_data, &patch_size))
       return false;
    if (patch_size < 0)