Seems to be related to the new breakpoints in JSSF:
Uncaught TypeError: Cannot read property 'remove' of null
at Sources.JavaScriptSourceFrame.onUISourceCodeContentChanged (chrome-devtools://devtools/bundled/sources/JavaScriptSourceFrame.js:179)
at Sources.JavaScriptSourceFrame._onWorkingCopyCommitted (chrome-devtools://devtools/bundled/sources/UISourceCodeFrame.js:240)
at Workspace.UISourceCode.dispatchEventToListeners (chrome-devtools://devtools/bundled/common/Object.js:98)
at Workspace.UISourceCode._contentCommitted (chrome-devtools://devtools/bundled/workspace/UISourceCode.js:350)
at Workspace.UISourceCode.contentLoaded (chrome-devtools://devtools/bundled/workspace/UISourceCode.js:292)
at FileReader.readerLoadEnd (chrome-devtools://devtools/bundled/workspace/IsolatedFileSystem.js:355)
Comment 1 by bugdroid1@chromium.org
, Dec 7 2016