tns reader fails with methoderror

```
using Finch
using TensorMarket # to read and write to files

TensorFile = "./facebook.tns"
B_COO = fread(TensorFile)
```

fails with:

```
ERROR: LoadError: MethodError: no method matching zero(::Type{Any})
This error has been manually thrown, explicitly, so the method may exist but be intentionally marked as unimplemented.
```