prompt: We are currently solving the following issue within our repository. Here is the issue text:
  --- BEGIN ISSUE ---
  Search on listing views doesn't work unless the `?q=` param exists in the URL
  <!--
  Found a bug? Please fill out the sections below. 👍
  -->
  
  ### Issue Summary
  
  Possible regression in https://github.com/wagtail/wagtail/pull/9768
  
  The `URLSearchParams.get()` returns `null` if the param doesn't exist, so the following code:
  
  https://github.com/wagtail/wagtail/blob/a3f10acae17c892d843c419495e4204adb3ed991/client/src/entrypoints/admin/core.js#L270-L276
  
  will crash during `currentQuery.trim()` when searching on the listing views (snippets, images, etc.) if the `?q=` param doesn't exist in the URL.
  
  Might be a good time to add `required=False` in here as well:
  
  https://github.com/wagtail/wagtail/blob/a3f10acae17c892d843c419495e4204adb3ed991/wagtail/admin/forms/search.py#L12
  
  to remove this silly error when `q` is an empty string:
  
  <img width="473" alt="image" src="https://user-images.githubusercontent.com/6379424/213499685-ce37c064-2635-434f-952f-e85fae4ab9af.png">
  
  <!--
  A summary of the issue.
  -->
  
  ### Steps to Reproduce
  
  1. Spin up bakerydemo
  2. Open the images listing
  3. Try to search
  
  
  --- END ISSUE ---
  
  Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
  --- BEGIN FILES ---
  Path: `wagtail/admin/forms/search.py`
  Content:
  ```
  1 from django import forms
  2 from django.utils.translation import gettext as _
  3 from django.utils.translation import gettext_lazy
  4 
  5 
  6 class SearchForm(forms.Form):
  7     def __init__(self, *args, **kwargs):
  8         placeholder = kwargs.pop("placeholder", _("Search"))
  9         super().__init__(*args, **kwargs)
  10         self.fields["q"].widget.attrs = {"placeholder": placeholder}
  11 
  12     q = forms.CharField(label=gettext_lazy("Search term"), widget=forms.TextInput())
  13
  ```
  --- END FILES ---
  
  Please first localize the bug based on the issue statement, and then generate a patch according to the `git diff` format fenced by three backticks.
  
  Here is an example:
  
  ```diff
  diff --git a/examples/server_async.py b/examples/server_async.py
  --- a/examples/server_async.py
  +++ b/examples/server_async.py
  @@ -313,4 +313,4 @@
   
   
   if __name__ == "__main__":
  -    asyncio.run(run_async_server("."), debug=True)
  +    asyncio.run(run_async_server(), debug=True)
  diff --git a/examples/server_sync.py b/examples/server_sync.py
  --- a/examples/server_sync.py
  +++ b/examples/server_sync.py
  @@ -313,5 +313,5 @@
   
   
   if __name__ == "__main__":
  -    server = run_sync_server(".")
  +    server = run_sync_server()
       server.shutdown()
  
  ```
  
golden_diff: diff --git a/wagtail/admin/forms/search.py b/wagtail/admin/forms/search.py
  --- a/wagtail/admin/forms/search.py
  +++ b/wagtail/admin/forms/search.py
  @@ -9,4 +9,8 @@
           super().__init__(*args, **kwargs)
           self.fields["q"].widget.attrs = {"placeholder": placeholder}
   
  -    q = forms.CharField(label=gettext_lazy("Search term"), widget=forms.TextInput())
  +    q = forms.CharField(
  +        label=gettext_lazy("Search term"),
  +        widget=forms.TextInput(),
  +        required=False,
  +    )
  
verification_info: {"golden_diff": "diff --git a/wagtail/admin/forms/search.py b/wagtail/admin/forms/search.py\n--- a/wagtail/admin/forms/search.py\n+++ b/wagtail/admin/forms/search.py\n@@ -9,4 +9,8 @@\n         super().__init__(*args, **kwargs)\n         self.fields[\"q\"].widget.attrs = {\"placeholder\": placeholder}\n \n-    q = forms.CharField(label=gettext_lazy(\"Search term\"), widget=forms.TextInput())\n+    q = forms.CharField(\n+        label=gettext_lazy(\"Search term\"),\n+        widget=forms.TextInput(),\n+        required=False,\n+    )\n", "issue": "Search on listing views doesn't work unless the `?q=` param exists in the URL\n<!--\r\nFound a bug? Please fill out the sections below. \ud83d\udc4d\r\n-->\r\n\r\n### Issue Summary\r\n\r\nPossible regression in https://github.com/wagtail/wagtail/pull/9768\r\n\r\nThe `URLSearchParams.get()` returns `null` if the param doesn't exist, so the following code:\r\n\r\nhttps://github.com/wagtail/wagtail/blob/a3f10acae17c892d843c419495e4204adb3ed991/client/src/entrypoints/admin/core.js#L270-L276\r\n\r\nwill crash during `currentQuery.trim()` when searching on the listing views (snippets, images, etc.) if the `?q=` param doesn't exist in the URL.\r\n\r\nMight be a good time to add `required=False` in here as well:\r\n\r\nhttps://github.com/wagtail/wagtail/blob/a3f10acae17c892d843c419495e4204adb3ed991/wagtail/admin/forms/search.py#L12\r\n\r\nto remove this silly error when `q` is an empty string:\r\n\r\n<img width=\"473\" alt=\"image\" src=\"https://user-images.githubusercontent.com/6379424/213499685-ce37c064-2635-434f-952f-e85fae4ab9af.png\">\r\n\r\n<!--\r\nA summary of the issue.\r\n-->\r\n\r\n### Steps to Reproduce\r\n\r\n1. Spin up bakerydemo\r\n2. Open the images listing\r\n3. Try to search\r\n\n", "before_files": [{"content": "from django import forms\nfrom django.utils.translation import gettext as _\nfrom django.utils.translation import gettext_lazy\n\n\nclass SearchForm(forms.Form):\n    def __init__(self, *args, **kwargs):\n        placeholder = kwargs.pop(\"placeholder\", _(\"Search\"))\n        super().__init__(*args, **kwargs)\n        self.fields[\"q\"].widget.attrs = {\"placeholder\": placeholder}\n\n    q = forms.CharField(label=gettext_lazy(\"Search term\"), widget=forms.TextInput())\n", "path": "wagtail/admin/forms/search.py"}], "after_files": [{"content": "from django import forms\nfrom django.utils.translation import gettext as _\nfrom django.utils.translation import gettext_lazy\n\n\nclass SearchForm(forms.Form):\n    def __init__(self, *args, **kwargs):\n        placeholder = kwargs.pop(\"placeholder\", _(\"Search\"))\n        super().__init__(*args, **kwargs)\n        self.fields[\"q\"].widget.attrs = {\"placeholder\": placeholder}\n\n    q = forms.CharField(\n        label=gettext_lazy(\"Search term\"),\n        widget=forms.TextInput(),\n        required=False,\n    )\n", "path": "wagtail/admin/forms/search.py"}]}