checker: fix panic on `fn abc()?{ return error() }`

vlib/v/checker/checker.v

@@ -2430,7 +2430,7 @@ pub fn (mut c Checker) fn_call(mut call_expr ast.CallExpr) ast.Type {
 		return func.return_type
 	}
 	// `return error(err)` -> `return err`
-	if fn_name == 'error' {
+	if fn_name == 'error' && call_expr.args.len == 1 {
 		arg := call_expr.args[0]
 		call_expr.args[0].typ = c.expr(arg.expr)
 		if call_expr.args[0].typ == ast.error_type {

vlib/v/checker/tests/error_fn_with_0_args.out

@@ -0,0 +1,5 @@
+vlib/v/checker/tests/error_fn_with_0_args.vv:2:9: error: expected 1 arguments, but got 0
+    1 | fn abc() ? {
+    2 |     return error()
+      |            ~~~~~~~
+    3 | }

vlib/v/checker/tests/error_fn_with_0_args.vv

@@ -0,0 +1,3 @@
+fn abc() ? {
+	return error()
+}