Checkboxes with bind:group break the page in some circumstances #8214
Description
Describe the bug
If you bind:group some checkboxes to a property of an object, and then set that property to undefined (or a boolean, etc.) then it will break the page, stopping all execution. I think it should not break.
REPL attached. I'll provide a PR.
Reproduction
https://svelte.dev/repl/842c52bdb62448d0866785eedc7c4fcd?version=3.55.1
Logs
Uncaught (in promise) TypeError: ctx[0] is undefined update CMSWidgetOptions.svelte:285 update CMSWidgetOptions.svelte:422 update CMSWidgetOptions.svelte:577 update index.mjs:1193 flush index.mjs:1160 promise callback*schedule_update index.mjs:1118 make_dirty index.mjs:1970 ctx index.mjs:2008 cmsfieldgroup_values_binding CMSWidgetEntity.svelte:2045 cmsfieldgroup_values_binding CMSWidgetEntity.svelte:1484 ctx index.mjs:2006 cmsfield_value_binding CMSFieldGroup.svelte:523 cmsfield_value_binding CMSFieldGroup.svelte:210 ctx index.mjs:2006 switch_instance_value_binding CMSField.svelte:735 switch_instance_value_binding CMSField.svelte:180 ctx index.mjs:2006 input_change_handler CMSWidgetOptions.svelte:656 listen index.mjs:415 listen_dev index.mjs:2160 mount CMSWidgetOptions.svelte:258 mount CMSWidgetOptions.svelte:402 mount CMSWidgetOptions.svelte:543 m svelte-hooks.js:291 mount_component index.mjs:1935 mount CMSField.svelte:217 mount CMSField.svelte:96 update CMSField.svelte:647 update index.mjs:1193 flush index.mjs:1160 promise callback*schedule_update index.mjs:1118 make_dirty index.mjs:1970 ctx index.mjs:2008 cmsfieldgroup_values_binding CMSWidgetEntity.svelte:2045 cmsfieldgroup_values_binding CMSWidgetEntity.svelte:1484 ctx index.mjs:2006 cmsfield_value_binding CMSFieldGroup.svelte:523 cmsfield_value_binding CMSFieldGroup.svelte:210 ctx index.mjs:2006 switch_instance_value_binding CMSField.svelte:735 switch_instance_value_binding CMSField.svelte:180 ctx index.mjs:2006 input_change_handler CMSWidgetCheckbox.svelte:400 listen index.mjs:415 listen_dev index.mjs:2160 mount CMSWidgetCheckbox.svelte:314 m svelte-hooks.js:291 mount_component index.mjs:1935 mount CMSField.svelte:217 mount CMSField.svelte:96 mount CMSField.svelte:631 m svelte-hooks.js:291 mount_component index.mjs:1935 mount CMSFieldGroup.svelte:234 mount CMSFieldGroup.svelte:361 m svelte-hooks.js:291 mount_component index.mjs:1935 mount CMSWidgetEntity.svelte:1537 mount Modal.svelte:105 m svelte-hooks.js:291System Info
System: OS: macOS 12.6.2 CPU: (8) x64 Apple M1 Memory: 27.68 MB / 8.00 GB Shell: 5.8.1 - /bin/zsh Binaries: Node: 16.15.1 - ~/.nvm/versions/node/v16.15.1/bin/node Yarn: 1.22.19 - /usr/local/bin/yarn npm: 8.11.0 - ~/.nvm/versions/node/v16.15.1/bin/npm Browsers: Chrome: 109.0.5414.87 Firefox: 108.0.2 Safari: 16.2 npmPackages: svelte: ^3.42.6 => 3.55.0Severity
annoyance