5 $p:druntime/import/core/internal/array/operations.d$($n$): Error: static assert: "Binary op `+=` not supported for types `string` and `string`."
6 $p:druntime/import/core/internal/array/operations.d$($n$): instantiated from here: `typeCheck!(true, string, string, "+=")`
7 $p:druntime/import/object.d$($n$): instantiated from here: `arrayOp!(string[], string[], "+=")`
8 fail_compilation/fail_arrayop3b.d(15): instantiated from here: `_arrayOp!(string[], string[], "+=")`