Trying to compile ``` class B { } interface I { } export class A extends B implements I { } ``` yields `Error [AssertionError]: assertion failed` which comes from https://github.com/AssemblyScript/assemblyscript/blob/af3b48985d8eb4c1ff8cbff8ad22776fea8299bc/src/program.ts#L1220 Is this intended? Looks like it should be supported.