The "Mode" select dropdown should also be read-only if the code field is

resources/js/components/fieldtypes/CodeFieldtype.vue

@@ -5,7 +5,7 @@
     <div class="code-fieldtype-container" :class="[themeClass, {'code-fullscreen': fullScreenMode }]">
         <div class="code-fieldtype-toolbar">
             <div>
-                <select-input v-if="config.mode_selectable" :options="modes" v-model="mode" class="text-xs leading-none" />
+                <select-input v-if="config.mode_selectable" :options="modes" v-model="mode" :is-read-only="isReadOnly" class="text-xs leading-none" />
                 <div v-else v-text="modeLabel" class="text-xs font-mono text-gray-700"></div>
             </div>
             <button @click="fullScreenMode = !fullScreenMode" class="btn-icon h-8 leading-none flex items-center justify-center text-gray-800" v-tooltip="__('Toggle Fullscreen Mode')">