Debugging wasm exceptions

OCCT failures compiled with native WASM exception handling reach JavaScript as WebAssembly.Exception values. Decode them through the initialized runtime:

import oc from 'libcascade';

try {
  using fillet = new oc.BRepFilletAPI_MakeFillet(badShape);
  fillet.Shape();
} catch (error: unknown) {
  if (error instanceof WebAssembly.Exception) {
    const [type, message] = oc.getExceptionMessage(error);
    console.error(`${type}: ${message}`);
  } else {
    throw error;
  }
}

error.message is not the C++ failure text. The helper returns a [type, message] tuple such as ['Standard_Failure', 'BRepFilletAPI_MakeFillet: Empty argument'].

Common failures

Debug builds

For source-level debugging, build with -g -fwasm-exceptions -O1 and use Chrome's WASM DWARF debugger.