Fix cursor moving to field start when closing MathJax editor

Closes #2258

ts/editor/mathjax-overlay/MathjaxOverlay.svelte

@@ -223,7 +223,8 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
                             resetHandle();
                         }}
                         on:blur={async () => {
-                            resetHandle();
+                            await tick();
+                            await resetHandle();
                         }}
                         on:close={resetHandle}
                         let:editor={mathjaxEditor}