Show better error message when trying to toggle with :set

doc/changelog.asciidoc

@@ -42,6 +42,11 @@ Fixed
 - Handle a filesystem going read-only gracefully
 - Fix wrong rendering of keys like `<back>` in the completion
 
+Changed
+~~~~~~~
+
+- Nicer error messages and other minor improvements
+
 v1.0.1
 ------
 

qutebrowser/config/configcommands.py

@@ -75,6 +75,10 @@ class ConfigCommands:
             tabbed_browser.openurl(QUrl('qute://settings'), newtab=False)
             return
 
+        if option.endswith('!'):
+            raise cmdexc.CommandError("Toggling values was moved to the "
+                                      ":config-cycle command")
+
         if option.endswith('?') and option != '?':
             self._print_value(option[:-1])
             return

tests/unit/config/test_configcommands.py

@@ -133,9 +133,9 @@ class TestSet:
                            "QtWebEngine backend!"):
             commands.set(0, 'content.cookies.accept', 'all')
 
-    @pytest.mark.parametrize('option', ['?', '!', 'url.auto_search'])
+    @pytest.mark.parametrize('option', ['?', 'url.auto_search'])
     def test_empty(self, commands, option):
-        """Run ':set ?' / ':set !' / ':set url.auto_search'.
+        """Run ':set ?' / ':set url.auto_search'.
 
         Should show an error.
         See https://github.com/qutebrowser/qutebrowser/issues/1109
@@ -145,6 +145,16 @@ class TestSet:
                                  "value"):
             commands.set(win_id=0, option=option)
 
+    def test_toggle(self, commands):
+        """Try toggling a value.
+
+        Should show an nicer error.
+        """
+        with pytest.raises(cmdexc.CommandError,
+                           match="Toggling values was moved to the "
+                                 ":config-cycle command"):
+            commands.set(win_id=0, option='javascript.enabled!')
+
     def test_invalid(self, commands):
         """Run ':set foo?'.