vfmt: print `or { }` on a single line

vlib/v/fmt/fmt.v

@@ -1073,10 +1073,14 @@ pub fn (mut f Fmt) or_expr(or_block ast.OrExpr) {
 	match or_block.kind {
 		.absent {}
 		.block {
+			if or_block.stmts.len == 0 {
+				f.write(' or { }')
+			} else {
 				f.writeln(' or {')
 				f.stmts(or_block.stmts)
 				f.write('}')
 			}
+		}
 		.propagate {
 			f.write('?')
 		}