Properly handle incorrect port numbers in parseURL (fixes #4200)

[ckeshava]

This Pull Request fixes issue 4200 (#4200).

Previously, inputs for very large port numbers (more than the 16 bit capacity of the field) was handled incorrectly i.e. lexicalCast returns a zero for such inputs.

The code in this PR returns a boolean value of false if the port number is zero.
This code also handles the case of an input of zero (0) to the port number field.

[ckeshava]

With regards to the failed Github Actions task, clang-format is not a recognised git command. Do I need to use an extension/tool (something like this? https://github.com/llvm-mirror/clang/blob/master/tools/clang-format/git-clang-format) to format my code?

[scottschurr]

I think you can use homebrew to install $ brew install clang-format. I always just try to remember to invoke clang-format before I push to my GitHub repo. There are other folks who have done something or other that is more automated.

[ckeshava]

Okay, thanks for the suggestion Scott! I'll look into that.