Fix support for Firefox and Safari

src/quiver.js

@@ -369,7 +369,6 @@ QuiverExport.tikz_cd = new class extends QuiverExport {
                     + TIKZ_VERTICAL_MULTIPLIER ** 2 * Math.cos(edge.angle()) ** 2) ** 0.5);
 
                 if (edge.options.curve !== 0) {
-                    has_curves = true;
                     parameters.push(
                         `curve={height=${
                             // Using a fixed multiplier for curves of any angle tends to work better

src/ui.js

@@ -5261,7 +5261,7 @@ class Edge extends Cell {
 
             for (const [key, value] of Object.entries(source)) {
                 if (typeof value === "object") {
-                    target[key] ||= {};
+                    target[key] = target[key] || {};
                     deep_assign(target[key], value);
                 } else {
                     target[key] = value;