Debug build crashes immediately

Debug builds of webengine 5.13 beta 1 crash immediately at startup (in both falkon and simplebrowser), with error:

[29608:29608:0320/163800.231100:FATAL:extension.cc(529)] Check failed: path.empty() || path.IsAbsolute().

and backtrace:

#0  base::debug::(anonymous namespace)::DebugBreak ()
   at ./../../../../qtwebengine-everywhere-src-5.13.0-beta1/src/3rdparty/chromium/base/debug/debugger_posix.cc:240
#1  0x00007fffecac5fb3 in base::debug::BreakDebugger ()
   at ./../../../../qtwebengine-everywhere-src-5.13.0-beta1/src/3rdparty/chromium/base/debug/debugger_posix.cc:263
#2  0x00007fffec9133f0 in logging::LogMessage::~LogMessage (this=0x7fffffffd8c0, __in_chrg=<optimized out>)
   at ./../../../../qtwebengine-everywhere-src-5.13.0-beta1/src/3rdparty/chromium/base/logging.cc:856
#3  0x00007ffff0e7efe8 in extensions::Extension::Extension (this=0x5555559a00b0, path=..., manifest=std::unique_ptr<extensions::Manifest> = {...})
   at ./../../../../qtwebengine-everywhere-src-5.13.0-beta1/src/3rdparty/chromium/extensions/common/extension.cc:529
#4  0x00007ffff0e7cbc8 in extensions::Extension::Create (path=..., location=extensions::Manifest::COMPONENT, value=..., flags=1, explicit_id="",  
   utf8_error=0x7fffffffde00) at ./../../../../qtwebengine-everywhere-src-5.13.0-beta1/src/3rdparty/chromium/extensions/common/extension.cc:174
#5  0x00007ffff0e7c8f1 in extensions::Extension::Create (path=..., location=extensions::Manifest::COMPONENT, value=..., flags=1,  
   utf8_error=0x7fffffffde00) at ./../../../../qtwebengine-everywhere-src-5.13.0-beta1/src/3rdparty/chromium/extensions/common/extension.cc:147
#6  0x00007fffe6f369d3 in extensions::ExtensionSystemQt::LoadExtension (this=this@entry=0x555555a95620, extension_id="mhjfbmdgcfjbbpaeojofohoefgiehjai",  
   manifest=std::unique_ptr<base::DictionaryValue> = {...}, directory=...) at /usr/include/c++/8.2.1/bits/unique_ptr.h:342
#7  0x00007fffe6f37338 in extensions::ExtensionSystemQt::Init (this=this@entry=0x555555a95620, extensions_enabled=extensions_enabled@entry=true)
   at /usr/include/c++/8.2.1/bits/basic_string.h:252
#8  0x00007fffe6f373f4 in extensions::ExtensionSystemQt::InitForRegularProfile (this=0x555555a95620, extensions_enabled=<optimized out>)
   at /build/qt5-webengine/src/qtwebengine-everywhere-src-5.13.0-beta1/src/core/extensions/extension_system_qt.cpp:398
#9  0x00007fffe6ecd1f7 in QtWebEngineCore::ProfileQt::ProfileQt (this=0x555555a94e50, profileAdapter=<optimized out>)
   at /build/qt5-webengine/src/qtwebengine-everywhere-src-5.13.0-beta1/src/core/profile_qt.cpp:139
#10 0x00007fffe6ec7b06 in QtWebEngineCore::ProfileAdapter::ProfileAdapter (this=0x555555a576c0, storageName=...)
   at /build/qt5-webengine/src/qtwebengine-everywhere-src-5.13.0-beta1/src/core/profile_adapter.cpp:96
#11 0x00007fffe6f08076 in QtWebEngineCore::WebEngineContext::createDefaultProfileAdapter (this=0x55555599abf0)
   at /build/qt5-webengine/src/qtwebengine-everywhere-src-5.13.0-beta1/src/core/web_engine_context.cpp:310
#12 0x00007fffe6ec4f6f in QtWebEngineCore::ProfileAdapter::createDefaultProfileAdapter ()
   at /build/qt5-webengine/src/qtwebengine-everywhere-src-5.13.0-beta1/src/core/profile_adapter.cpp:235
#13 0x00007ffff7f6853e in QWebEngineProfile::defaultProfile ()
-Type <RET> for more, q to quit, c to continue without paging-
   at /build/qt5-webengine/src/qtwebengine-everywhere-src-5.13.0-beta1/src/webenginewidgets/api/qwebengineprofile.cpp:691
#14 0x00007ffff7f6dbbb in QWebEngineSettings::defaultSettings ()
   at /build/qt5-webengine/src/qtwebengine-everywhere-src-5.13.0-beta1/src/webenginewidgets/api/qwebenginesettings.cpp:144
#15 0x00005555555625be in main ()