Just got the same bug:
Just loaded the .capx and tried to preview, then .......
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Construct 2 Check failure
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Check failure! This is probably a bug:
Unknown fullscreen-in-browser setting
Condition: false
File: DataJSON.cpp
Line: 324
Function: void __thiscall Exporter::ProjectToJSON(class std::basic_ostringstream<wchar_t,struct std::char_traits<wchar_t>,class std::allocator<wchar_t> > &,class era::IProject *,class era::ILayout *)
Build: release 75 (32-bit) checked
Component: HTML5 exporter
(Last Win32 error: 0)
You are using a 'checked' release of Construct 2, intended for testing, which causes certain errors to be reported this way. Hit Ctrl+C to copy this messagebox - it's useful information for the developers, so please include it with any bug reports! Click 'Abort' to quit (unsaved data will be lost!),'Retry' to turn off messages for this session and continue, or 'Ignore' to continue normally.
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Abort Retry Ignore
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.capx HERE.