src/vs/workbench/services/workingCopy/common/storedFileWorkingCopy.ts/StoredFileWorkingCopy/isTextFileModel
class StoredFileWorkingCopy:	private isTextFileModel(model: unknown): model is ITextFileEditorModel {
		const textFileModel = this.textFileService.files.get(this.resource);

		return !!(textFileModel && this.model && (textFileModel as unknown) === (this.model as unknown));
	}