Confusing read() error for absolute Windows path arg

[arlowhite]

GeoDataFrames version 0.3.10

In Windows, if you call read with an absolute path where file does not exist, you get a confusing error. This could confuse and frustrate Windows users.

GeoDataFrames.read("C:\\foo")

ERROR: GDALError (CE_Failure, code 10): Pointer 'hDS' is NULL in 'GDALDatasetH'.

This is due to the colon in the file path.

https://github.com/evetion/GeoDataFrames.jl/blob/master/src/io.jl#L52

function read(fn::AbstractString; kwargs...)
    startswith(fn, "/vsi") ||
        occursin(":", fn) ||
        isfile(fn) ||
        isdir(fn) ||
        error("File not found.")
    t = AG.read(fn; kwargs...) do ds
        if AG.nlayer(ds) > 1
            @warn "This file has multiple layers, you only get the first layer by default now."
        end
        return read(ds, 0)
    end
    return t
end

---

: in fn causes error to be skipped at occursin(":", fn) . Then AG.nlayer(ds) results in this confusing error. ds

NULL Dataset

typeof(ds)

ArchGDAL.Dataset

Note: you could check for NULL Dataset with ds.ptr == C_NULL

[arlowhite]

Though it's strange, because this has a clear error: ArchGDAL.read("C:\\foo")

ERROR: GDALError (CE_Failure, code 4): C:\foo: No such file or directory

[evetion]

Thanks for reporting! With adding : I overlooked Windows paths it seems. Would you like to make a PR?