builtin: show non zero codes on bubbled error_with_code(msg,code) errors

vlib/builtin/option.v

@@ -55,6 +55,9 @@ pub:
 
 // msg returns the message of MessageError
 pub fn (err MessageError) msg() string {
+	if err.code > 0 {
+		return '$err.msg; code: $err.code'
+	}
 	return err.msg
 }
 

vlib/os/signal_test.v

@@ -20,7 +20,7 @@ fn test_signal_opt_invalid_argument() {
 		assert false
 	}
 	os.signal_opt(.kill, default_handler) or {
-		assert err.msg() == 'Invalid argument'
+		assert err.msg() == 'Invalid argument; code: 22'
 		assert err.code() == 22
 	}
 }

vlib/v/tests/option_test.v

@@ -1,18 +1,19 @@
-fn opt_err_with_code() ?string {
-	return error_with_code('hi', 137)
+// TODO: remove this after the deprecation period for `?Type` representing both Result and Option passes.
+fn opt_err_with_code(code int) ?string {
+	return error_with_code('hi', code)
 }
 
 fn test_err_with_code() {
-	if w := opt_err_with_code() {
+	if w := opt_err_with_code(137) {
 		assert false
 		_ := w
 	} else {
-		assert err.msg() == 'hi'
+		assert err.msg() == 'hi; code: 137'
 		assert err.code() == 137
 	}
-	v := opt_err_with_code() or {
-		assert err.msg() == 'hi'
-		assert err.code() == 137
+	v := opt_err_with_code(56) or {
+		assert err.msg() == 'hi; code: 56'
+		assert err.code() == 56
 		return
 	}
 	assert false

vlib/v/tests/results_test.v

@@ -94,3 +94,24 @@ fn test_results_if_guard() {
 	}
 	assert false
 }
+
+fn res_err_with_code(code int) !string {
+	return error_with_code('hi', code)
+}
+
+fn test_err_with_code() {
+	if w := res_err_with_code(137) {
+		assert false
+		_ := w
+	} else {
+		assert err.msg() == 'hi; code: 137'
+		assert err.code() == 137
+	}
+	v := res_err_with_code(56) or {
+		assert err.msg() == 'hi; code: 56'
+		assert err.code() == 56
+		return
+	}
+	assert false
+	_ := v
+}