Can't load GDNative compiled for javascript target

After export game or run it from editor by HTML5 button, I see this error:

index.js:362 ERROR: Can't open dynamic library: bin/javascript64/TinyRTSGDNative.wasm. Error: Could not load dynamic lib: TinyRTSGDNative.wasm
index.js:362 Error: TinyRTSGDNative.wasm: file not found, and synchronous loading of external files is not available
index.js:362 at: open_dynamic_library (platform/javascript/os_javascript.cpp:1054) - Condition "!p_library_handle" is true. Returned: ERR_CANT_OPEN
index.js:362 ERROR: No valid library handle, can't get symbol from GDNative object
index.js:362 at: get_symbol (modules/gdnative/gdnative.cpp:510) - No valid library handle, can't get symbol from GDNative object
index.js:362 ERROR: No nativescript_init in "res://bin/javascript64/TinyRTSGDNative.wasm" found
index.js:362 at: init_library (modules/gdnative/nativescript/nativescript.cpp:1510) - No nativescript_init in "res://bin/javascript64/TinyRTSGDNative.wasm" found

Compiled with latest emscripten and included like windows-version of library which works.

How to load the wasm library? Looks like it is not icluded to exported game.