[FIX] account: fix bug when opening a misc journal entry

Before this commit, opening a misc journal entry resulted in an error because we tried
to compute the tax totals as if it was an invoice.

This commit ignores the computation of these tax totals in case we have a misc journaly entry.

opw-2946634

closes odoo/odoo#97600

Signed-off-by: Florian Gilbert (flg) <flg@odoo.com>

addons/account/static/src/js/legacy_tax_totals.js

@@ -159,6 +159,8 @@ class LegacyTaxTotalsComponent extends AbstractFieldOwl {
     }
 
     _computeTotalsFormat() {
+        if (!this.totals.value) // Misc journal entry
+            return;
         let amount_untaxed = this.totals.value.amount_untaxed;
         let amount_tax = 0;
         let subtotals = [];