parser: fix fmt error for json decode (#14520)

vlib/v/fmt/tests/json_decode_fmt_keep.vv

@@ -0,0 +1,19 @@
+import json
+
+struct Request {
+	a int
+}
+
+fn parse(s string) ?Request {
+	return json.decode(Request, s)
+}
+
+fn parse2(s string) ?Request {
+	req := json.decode(Request, s)?
+	return req
+}
+
+fn main() {
+	println(parse('{"a": 22} ')?)
+	println(parse2('{"a": 22} ')?)
+}

vlib/v/parser/fn.v

@@ -24,7 +24,6 @@ pub fn (mut p Parser) call_expr(language ast.Language, mod string) ast.CallExpr
 	mut or_kind := ast.OrKind.absent
 	if fn_name == 'json.decode' {
 		p.expecting_type = true // Makes name_expr() parse the type `User` in `json.decode(User, txt)`
-		or_kind = .block
 	}
 
 	old_expr_mod := p.expr_mod