small fixes on example

lib/vfs/vfsnested/vfsnested.v

@@ -111,8 +111,8 @@ pub fn (mut self NestedVFS) dir_delete(path string) ! {
 	return impl.dir_delete(rel_path)
 }
 
-pub fn (mut self NestedVFS) exists(path string) !bool {
-	mut impl, rel_path := self.find_vfs(path)!
+pub fn (mut self NestedVFS) exists(path string) bool {
+	mut impl, rel_path := self.find_vfs(path) or {return false}
 	return impl.exists(rel_path)
 }
 

lib/vfs/vfsourdb/vfsourdb.v

@@ -96,7 +96,7 @@ pub fn (mut self OurDBVFS) dir_delete(path string) ! {
 	parent_dir.rm(dir_name)!
 }
 
-pub fn (mut self OurDBVFS) exists(path string) !bool {
+pub fn (mut self OurDBVFS) exists(path string) bool {
 	if path == '/' {
 		return true
 	}