fix crash while building geometry of multipolygon with zero-node way members

[tyrasd]

this bug occurs when the following two conditions are met:

• a multipolygon refers to a member which at the given timestamp has zero nodes
  • example: https://www.openstreetmap.org/api/0.6/relation/22050/history at 2008-09-30T10:00:52Z contains https://www.openstreetmap.org/api/0.6/way/25714579/6 which has zero nodes
  • AFAIK only old versions of the OSM API allowed such "invalid" ways to exists. Now there is a check in place which prevents these corner cases
• the order of the relation members is such that the 0-node member's previous members do not form a closed loop

Checklist

• My code follows the code-style rules, and I have checked on the static analyses and benchmark (if applicable) results
• I have commented my code
• I have written javadoc (required for public classes and methods)
• I have added sufficient unit tests
• I have made corresponding changes to the documentation
• I have updated the CHANGELOG.md
• I have adjusted the examples or created an issue in the corresponding repository
• I have adjusted the benchmark or created an issue in the corresponding repository

[rtroilo]

💯