Hey guys,
Yesterday authoring stopped working in the middle of the day. No changes had been made that we are aware of.
Navigating to the page through sites.html seems to work find but when you select a page and click edit, you just get a blank screen. Chrome's dev-tools shows the following errors:

When I look through the author logs, I see these exceptions:
2020-04-22 08:34:09,783 *ERROR* [96.37.61.251 [1587562449589] GET /libs/clientlibs/granite/richtext.min.js HTTP/1.1] com.adobe.granite.ui.clientlibs.impl.HtmlLibraryManagerImpl Error during assembly of library.
org.mozilla.javascript.EvaluatorException: Compilation produced 27 syntax errors.
at com.adobe.granite.ui.clientlibs.impl.YUIScriptProcessor$1.runtimeError(YUIScriptProcessor.java:146)
at org.mozilla.javascript.Parser.parse(Parser.java:396)
at org.mozilla.javascript.Parser.parse(Parser.java:340)
at com.yahoo.platform.yui.compressor.JavaScriptCompressor.parse(JavaScriptCompressor.java:315)
at com.yahoo.platform.yui.compressor.JavaScriptCompressor.<init>(JavaScriptCompressor.java:536)
at com.adobe.granite.ui.clientlibs.impl.YUIScriptProcessor.minifyJS(YUIScriptProcessor.java:122)
at com.adobe.granite.ui.clientlibs.impl.YUIScriptProcessor.process(YUIScriptProcessor.java:117)
at com.adobe.granite.ui.clientlibs.impl.HtmlLibraryBuilderImpl.processSources(HtmlLibraryBuilderImpl.java:122)
at com.adobe.granite.ui.clientlibs.impl.HtmlLibraryBuilderImpl.processSources(HtmlLibraryBuilderImpl.java:87)
at com.adobe.granite.ui.clientlibs.impl.HtmlLibraryBuilderImpl.build(HtmlLibraryBuilderImpl.java:135)
at com.adobe.granite.ui.clientlibs.impl.HtmlLibraryManagerImpl.update(HtmlLibraryManagerImpl.java:1411)
at com.adobe.granite.ui.clientlibs.impl.HtmlLibraryManagerImpl.getOrCreateCacheResource(HtmlLibraryManagerImpl.java:1352)
at com.adobe.granite.ui.clientlibs.impl.HtmlLibraryManagerImpl.send(HtmlLibraryManagerImpl.java:1283)
at com.adobe.granite.ui.clientlibs.impl.HtmlLibraryWriter.send(HtmlLibraryWriter.java:571)
at com.adobe.granite.ui.clientlibs.impl.HtmlLibraryImpl.send(HtmlLibraryImpl.java:170)
at com.adobe.granite.ui.clientlibs.impl.HtmlLibraryServlet.doGet(HtmlLibraryServlet.java:91)
at org.apache.sling.api.servlets.SlingSafeMethodsServlet.mayService(SlingSafeMethodsServlet.java:266)
at org.apache.sling.api.servlets.SlingSafeMethodsServlet.service(SlingSafeMethodsServlet.java:342)
at org.apache.sling.api.servlets.SlingSafeMethodsServlet.service(SlingSafeMethodsServlet.java:374)
at org.apache.sling.engine.impl.request.RequestData.service(RequestData.java:552)
at org.apache.sling.engine.impl.filter.SlingComponentFilterChain.render(SlingComponentFilterChain.java:44)
at org.apache.sling.engine.impl.filter.AbstractSlingFilterChain.doFilter(AbstractSlingFilterChain.java:77)
...
2020-04-22 08:34:09,784 *INFO* [96.37.61.251 [1587562449589] GET /libs/clientlibs/granite/richtext.min.js HTTP/1.1] com.adobe.granite.ui.clientlibs.impl.LibraryCacheImpl Invalidating library /libs/clientlibs/granite/richtext
2020-04-22 08:34:09,793 *INFO* [96.37.61.251 [1587562449589] GET /libs/clientlibs/granite/richtext.min.js HTTP/1.1] com.adobe.granite.ui.clientlibs.impl.HtmlLibraryManagerImpl detected [JS, CSS] library: /libs/clientlibs/granite/richtext, sourced from 50 files.
2020-04-22 08:34:09,793 *ERROR* [96.37.61.251 [1587562449589] GET /libs/clientlibs/granite/richtext.min.js HTTP/1.1] com.adobe.granite.ui.clientlibs.impl.HtmlLibraryManagerImpl Error while saving changes: javax.jcr.RepositoryException: Error during assembly of /libs/clientlibs/granite/richtext.js. reverting.
2020-04-22 08:34:09,793 *ERROR* [96.37.61.251 [1587562449589] GET /libs/clientlibs/granite/richtext.min.js HTTP/1.1] com.adobe.granite.ui.clientlibs.impl.HtmlLibraryManagerImpl Error while sending cached library: javax.jcr.RepositoryException: Error during assembly of /libs/clientlibs/granite/richtext.js
2020-04-22 08:34:09,794 *ERROR* [96.37.61.251 [1587562449589] GET /libs/clientlibs/granite/richtext.min.js HTTP/1.1] com.adobe.granite.ui.clientlibs.impl.HtmlLibraryServlet Cannot create library for /libs/clientlibs/granite/richtext.min.js
java.io.IOException: Error while sending cached library: javax.jcr.RepositoryException: Error during assembly of /libs/clientlibs/granite/richtext.js
at com.adobe.granite.ui.clientlibs.impl.HtmlLibraryManagerImpl.send(HtmlLibraryManagerImpl.java:1301)
at com.adobe.granite.ui.clientlibs.impl.HtmlLibraryWriter.send(HtmlLibraryWriter.java:571)
at com.adobe.granite.ui.clientlibs.impl.HtmlLibraryImpl.send(HtmlLibraryImpl.java:170)
at com.adobe.granite.ui.clientlibs.impl.HtmlLibraryServlet.doGet(HtmlLibraryServlet.java:91)
at org.apache.sling.api.servlets.SlingSafeMethodsServlet.mayService(SlingSafeMethodsServlet.java:266)
at org.apache.sling.api.servlets.SlingSafeMethodsServlet.service(SlingSafeMethodsServlet.java:342)
at org.apache.sling.api.servlets.SlingSafeMethodsServlet.service(SlingSafeMethodsServlet.java:374)
at org.apache.sling.engine.impl.request.RequestData.service(RequestData.java:552)
at org.apache.sling.engine.impl.filter.SlingComponentFilterChain.render(SlingComponentFilterChain.java:44)
at org.apache.sling.engine.impl.filter.AbstractSlingFilterChain.doFilter(AbstractSlingFilterChain.java:77)
at com.adobe.acs.commons.wcm.impl.ComponentErrorHandlerImpl.doFilter(ComponentErrorHandlerImpl.java:192)
at org.apache.sling.engine.impl.filter.AbstractSlingFilterChain.doFilter(AbstractSlingFilterChain.java:68)
at com.day.cq.wcm.core.impl.WCMDebugFilter.doFilter(WCMDebugFilter.java:138)
at org.apache.sling.engine.impl.filter.AbstractSlingFilterChain.doFilter(AbstractSlingFilterChain.java:68)
at com.day.cq.wcm.core.impl.WCMComponentFilter.filterRootInclude(WCMComponentFilter.java:375)
at com.day.cq.wcm.core.impl.WCMComponentFilter.doFilter(WCMComponentFilter.java:190)
at org.apache.sling.engine.impl.filter.AbstractSlingFilterChain.doFilter(AbstractSlingFilterChain.java:68)
at com.day.cq.wcm.core.impl.PageLockFilter.doFilter(PageLockFilter.java:91)
..
Any help is much appreciated!!!