Uncaught runtime errors, Unknown promise rejection reason

[contactshahzadh1]

I am using Itwin viewer, below are dependencies in my React application, i am getting the below error "Uncaught runtime errors, Unknown promise rejection reason" on my screen sometimes. Please advise.

"@bentley/icons-generic": "^1.0.34",
"@bentley/react-scripts": "^5.0.7",
"@emotion/react": "^11.14.0",
"@emotion/styled": "^11.14.0",
"@itwin/appui-abstract": "^4.10.4",
"@itwin/appui-layout-react": "^4.8.3",
"@itwin/appui-react": "^4.17.6",
"@itwin/browser-authorization": "^1.1.4",
"@itwin/components-react": "^4.17.6",
"@itwin/core-bentley": "^4.10.4",
"@itwin/core-common": "^4.10.4",
"@itwin/core-frontend": "^4.10.4",
"@itwin/core-geometry": "^4.10.4",
"@itwin/core-i18n": "^4.10.4",
"@itwin/core-markup": "^4.10.4",
"@itwin/core-orbitgt": "^4.10.4",
"@itwin/core-quantity": "^4.10.4",
"@itwin/core-react": "^4.17.6",
"@itwin/core-telemetry": "^4.10.4",
"@itwin/ecschema-metadata": "^4.10.4",
"@itwin/ecschema-rpcinterface-common": "^4.10.4",
"@itwin/imodel-components-react": "^4.17.6",
"@itwin/imodels-access-frontend": "^4.1.6",
"@itwin/itwins-client": "^1.6.1",
"@itwin/itwinui-css": "^2.5.0",
"@itwin/itwinui-react": "^2.12.26",

[ben-polinsky]

Hi.
Could you provide a bit more context?

• Do you have more logging in either the browser dev console or terminal console?
• Was this created from the cra-web-viewer template?

[contactshahzadh1]

Hi Ben,
I have attached the console log for your reference, my application writes to the log so there are details from my application as well.
You would need to ignore that.
The sample was generated by following the instructions on: https://developer.bentley.com/tutorials/get-started-with-itwin-platform/
localhost-1740583993750.zip

[ben-polinsky]

Thanks - nothing is jumping out at me.

• Is this a desktop or web application?
• Is the issue reproducible without changes to the above instructions to set up a viewer?

[contactshahzadh1]

Yes the error is reproducible, actually in the sample i can see that there is a new promise raised to check if the tree is loaded. Since the React application re-renders whenever the itwinid & the imodelid changes, hence the below code is called often. Also my application has some 8-10 itwins/imodels for the user to select and when he keeps selecting, the below code is called multiple times, maybe the Promise rejection is happening in this part of the code, this is my suspicion, maybe you can clarify this for me.

const tileTreesLoaded = () => {
  return new Promise((resolve, reject) => {
    const start = new Date();
    const intvl = setInterval(() => {
      if (viewPort.areAllTileTreesLoaded) {
        ViewerPerformance.addMark("TilesLoaded");
        ViewerPerformance.addMeasure(
          "TileTreesLoaded",
          "ViewerStarting",
          "TilesLoaded"
        );
        clearInterval(intvl);
        resolve(true);
      }
      const now = new Date();
      // after 20 seconds, stop waiting and fit the view
      if (now.getTime() - start.getTime() > 20000) {
        reject();
      }
    }, 100);
  });
};

tileTreesLoaded().finally(() => {
  void IModelApp.tools.run(FitViewTool.toolId, viewPort, true, false);
  viewPort.view.setStandardRotation(StandardViewId.Iso);
});

}, []);

[ben-polinsky]

You can try catching the error to see if that helps. It could be possible that when the component re-renders due to an iTwin/iModel change, the interval isn't cleared. In that case, you'd want to ensure you call clearInterval on the timeout (would have to rearrange the code depending on your implementation).

None of this code is strictly necessary, though. It's all a convenience to fit the view once tiles have loaded.