Conan

When I try to 'conan install' version-range-based requirements for a package from a GitLab remote package repository, I get an unhelpful Python message "ERROR: 'NoneType' object is not iterable." I believe it's triggered by some faulty implementation on the GitLab repository side, but it would be helpful if Conan provided a more specific indication of the error cause.
My example conanfile.py:
`

The documentation says this "Even though mp-units library does not implement any Linear Algebra types it is generic enough to be used with other Linear Algebra libraries existing on the market.". A set of examples using Eigen would be helpful. Blaze would probably be good too, but personally I don't use it so it's a lower priority for me.

Package and Environment Details (include every applicable attribute)

• Package Name/Version: openssl/1.1.1d
• Operating System+version: Linux CentOS 7.7.1908
• Compiler+version: GCC 7.3.1 (devtoolset-7)
• Docker image: **centos:7.7.190

• add instructions for using doxygen-docs target
• add instructions for using sanitizers (especially on windows)
• adding more examples for using the options:
  • using PCH headers
  • using coverage
  • overriding compiler warnings,
  • adding more warnings
  • removing certain warnings for certain targets
• documenting the individual functions (e.g. enable

The example in https://docs.conan.io/en/latest/integrations/ci/appveyor.html is invalid (indentation, cmmd). I am new to appveyor. I guess it should be:

version: 1.0.{build}
platform:
  - x64

install:
  - cmd: echo "Downloading conan..."
  - cmd: set PATH=%PATH%;%PYTHON%/Scripts/
  - cmd: pip.exe install conan
  - cmd: conan user # Create the conan data directory
  - cmd: cona