Is it okay to use assertions in production?

I often read about assertions as something that should happen in debugging. Is it good practice to use TypeScript assertions in practice? If not, why not?

Below is an example where I would like to use an assertion in production.

The type of win needs to be BrowserWindow | null because the variable is declared before the BrowserWindow is created and assigned. But at the point in the code where I use assertIsBrowserWindow, I expect that win is now of type BrowserWindow, otherwise something has gone horribly wrong. assertIs* seems like a nice syntax to me here.

let win: BrowserWindow | null = null;

function createWindow() {
  win = new BrowserWindow();

  win.webContents.on("did-finish-load", () => {
    assertIsBrowserWindow(win);
    win.show();
    win.maximize();
  });
}

function assertIsBrowserWindow(val: any): asserts val is BrowserWindow {
  if (!(win instanceof BrowserWindow)) {
    throw new Error("Expected window");
  }
}

Here is another example:

// The only allowed values for an input group is FileSystemEntryType values. 

<input
  type="radio"
  value={FileSystemEntryType.Directory}
  checked={state.selectionMode === FileSystemEntryType.Directory}
  onChange={onSelectionModeChanged}
/>

// The onChange handler receives a string in the event, since coming from HTML world, the value can be any string. I had a switch case statement before that defaulted to an error. Now I use the shorter assert syntax instead.

const onSelectionModeChanged = (e: React.ChangeEvent<HTMLInputElement>) => {
  const selectionMode = Number.parseInt(e.currentTarget.value);
  assertIsFileSystemEntryType(Number.parseInt(e.currentTarget.value));
  dispatch({ type: "UPDATE_SELECTION_MODE", selectionMode: selectionMode });
};

// Supporting code

export enum FileSystemEntryType {
  File,
  Directory,
}

export function assertIsFileSystemEntryType(val: any): asserts val is FileSystemEntryType {
  if (!Object.values(FileSystemEntryType).includes(val)) {
    throw new Error(`Expected ${val} to have type FileSystemEntryType`);
  }
}