`assertIsDefined` vs `assertDefined`

I think for a developer on VS Code its impossible to understand the difference, given the names are so similar. Can we make this more explicit to distinguish?

https://github.com/microsoft/vscode/blob/dac0c97d082bd3bf38fdb3251e955e25c7c992a0/src/vs/base/common/types.ts#L102

https://github.com/microsoft/vscode/blob/dac0c97d082bd3bf38fdb3251e955e25c7c992a0/src/vs/base/common/types.ts#L137