Add error handling for invalid selectors

qutebrowser/browser/browsertab.py

@@ -632,6 +632,9 @@ class AbstractElements:
     def find_css(self, selector, callback, *, only_visible=False):
         """Find all HTML elements matching a given selector async.
 
+        If there's an error, the callback is called with a webelem.Error
+        instance.
+
         Args:
             callback: The callback to be called when the search finished.
             selector: The CSS selector to search for.

qutebrowser/browser/hints.py

@@ -601,8 +601,12 @@ class HintManager(QObject):
             return
 
         if elems is None:
-            message.error("There was an error while getting hint elements")
+            message.error("Unknown error while getting hint elements.")
             return
+        elif isinstance(elems, webelem.Error):
+            message.error(str(elems))
+            return
+
         if not elems:
             message.error("No elements found.")
             return

qutebrowser/browser/navigate.py

@@ -21,6 +21,7 @@
 
 import posixpath
 
+from qutebrowser.browser import webelem
 from qutebrowser.config import config
 from qutebrowser.utils import objreg, urlutils, log, message, qtutils
 from qutebrowser.mainwindow import mainwindow
@@ -116,7 +117,10 @@ def prevnext(*, browsertab, win_id, baseurl, prev=False,
     """
     def _prevnext_cb(elems):
         if elems is None:
-            message.error("There was an error while getting hint elements")
+            message.error("Unknown error while getting hint elements")
+            return
+        elif isinstance(elems, webelem.Error):
+            message.error(str(elems))
             return
 
         elem = _find_prevnext(prev, elems)

qutebrowser/browser/webengine/webenginetab.py

@@ -596,9 +596,12 @@ class WebEngineElements(browsertab.AbstractElements):
         if js_elems is None:
             callback(None)
             return
+        elif not js_elems['success']:
+            callback(webelem.Error(js_elems['error']))
+            return
 
         elems = []
-        for js_elem in js_elems:
+        for js_elem in js_elems['result']:
             elem = webengineelem.WebEngineElement(js_elem, tab=self._tab)
             elems.append(elem)
         callback(elems)

qutebrowser/javascript/webelem.js

@@ -214,7 +214,14 @@ window._qutebrowser.webelem = (function() {
     }
 
     funcs.find_css = (selector, only_visible) => {
-        const elems = document.querySelectorAll(selector);
+        let elems;
+
+        try {
+            elems = document.querySelectorAll(selector);
+        } catch (ex) {
+            return {"success": false, "error": ex.toString()};
+        }
+
         const subelem_frames = window.frames;
         const out = [];
 
@@ -239,7 +246,7 @@ window._qutebrowser.webelem = (function() {
             }
         }
 
-        return out;
+        return {"success": true, "result": out};
     };
 
     // Runs a function in a frame until the result is not null, then return

tests/end2end/features/hints.feature

@@ -213,6 +213,13 @@ Feature: Using hints
         And I hint with args "custom" and follow a
         Then the javascript message "beep!" should be logged
 
+    @qtwebkit_skip
+    Scenario: Invalid custom selector
+        When I open data/hints/custom_group.html
+        And I set hints.selectors to {"custom":["@"]}
+        And I run :hint custom
+        Then the error "SyntaxError: Failed to execute 'querySelectorAll' on 'Document': '@' is not a valid selector." should be shown
+
     # https://github.com/qutebrowser/qutebrowser/issues/1613
     Scenario: Hinting inputs with padding
         When I open data/hints/input.html

tests/end2end/features/navigate.feature

@@ -75,6 +75,11 @@ Feature: Using :navigate
         And I run :navigate next
         Then data/navigate/next.html should be loaded
 
+    Scenario: Navigating with invalid selector
+        When I set hints.selectors to {"links": ["@"]}
+        And I run :navigate next
+        Then the error "SyntaxError: Failed to execute 'querySelectorAll' on 'Document': '@' is not a valid selector." should be shown
+
     # increment/decrement
 
     Scenario: Incrementing number in URL