TypeScript Version: 2.5.0
Code
const a: (d: string) => number = (d) => d.length;
const b: (d?: string) => number = a;
b();
Expected behavior:
When compiled with --strict, the assignment of b should cause a type error along the lines of:
string | undefined is not assignable to type string.
Actual behavior:
The code compiles with --strict, then throws an exception at runtime on the expression d.length.
TypeScript Version: 2.5.0
Code
Expected behavior:
When compiled with
--strict, the assignment ofbshould cause a type error along the lines of:Actual behavior:
The code compiles with
--strict, then throws an exception at runtime on the expressiond.length.