fix console stack traces for errors from plugins

Summary:
We had our stack traces broken for a long time. They always pointed at the bundle.js file. With this change the stack traces **in the console** will be pointing at the actual source files. This will save a lot of time for engineers instead of manually looking for the source of errors.

Why this didn't work before?

When we were calling `console.error(error.toString())` the browser was not applying sourcemaps to the stacktrace as it interpreted as a random string. However, when you pass an actual instance of Error constructor, the sourcemaps will be applied and we get correct stack traces to the source files.

I looked at the code of the Logger and it is already handles the Error instances, so I think this should be fine also for the logs that go to scuba. CC passy

Reviewed By: LukeDefeo, passy

Differential Revision: D49275025

fbshipit-source-id: 2addc601f45622e35890d7d0e1992f4bca41a338

desktop/flipper-ui-core/src/ui/components/ErrorBoundary.tsx

@@ -55,7 +55,8 @@ export default class ErrorBoundary extends Component<
   }
 
   componentDidCatch(err: Error, errorInfo: ErrorInfo) {
-    console.error(err.toString(), errorInfo.componentStack, 'ErrorBoundary');
+    // eslint-disable-next-line flipper/no-console-error-without-context
+    console.error(err, errorInfo.componentStack, 'ErrorBoundary');
     this.setState({error: err});
   }
 
@@ -78,11 +79,9 @@ export default class ErrorBoundary extends Component<
       return (
         <ErrorBoundaryContainer grow>
           <Heading>{heading}</Heading>
-          {this.props.showStack !== false && (
+          {this.props.showStack !== false &&
-            <ErrorBoundaryStack>{`${
+            'Look in the console for correct stack traces.'}
-              error.stack ?? error.toString()
+          <br />
-            }`}</ErrorBoundaryStack>
-          )}
           <Button onClick={this.clearError}>Clear error and try again</Button>
         </ErrorBoundaryContainer>
       );