How can I filter out errors from the Firefox Browser Console?
<p>I'm using Greasemonkey, which sends errors to the Browser Console. I'm accessing this console by typing <kbd>Ctrl+Shift+J</kbd>. </p>

<p>The <a href="https://developer.mozilla.org/en-US/docs/Tools/Browser_Console" rel="noreferrer">MDN docs</a> contain links to <a href="https://developer.mozilla.org/en-US/docs/Tools/Web_Console#Filtering_and_searching" rel="noreferrer">https://developer.mozilla.org/en-US/docs/Tools/Web_Console#Filtering_and_searching</a> , but the link lands on a generic page. I am trying to filter out never-ending errors that look like:</p>

<pre><code>10:26:36.122 Error: Permission denied to access property "postMessage"
g.L() www-widgetapi.js:94
g.P() www-widgetapi.js:91
1 www-widgetapi.js:94:312
</code></pre>

<p>I tried typing "-widget", "~widget", and "-permission" in the "filter output" toolbar, but they all screen out everything, such as errors of the form "missing { before try block". How can I make a filter that <em>ex</em>cludes, instead of <em>in</em>cludes?</p>