Raises an error on empty dimension

[hrmorley34]

This is a very minor thing, but when you attempt to draw up an emtpy dimension, it raises an exception: Sequence contains no elements.

Opening world...
Generating a list of all chunk keys in the database.
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Total Chunk count 0

Unhandled exception. System.InvalidOperationException: Sequence contains no elements
   at System.Linq.ThrowHelper.ThrowNoElementsException()
   at System.Linq.Enumerable.Min[TSource](IEnumerable`1 source, Func`2 selector)
   at PapyrusCs.Program.RunMapCommand(Options options) in C:\projects\papyruscs-19426\PapyrusCs\Program.cs:line 396
   at PapyrusCs.Program.<>c.<Main>b__4_0(Options opts) in C:\projects\papyruscs-19426\PapyrusCs\Program.cs:line 49
   at CommandLine.ParserResultExtensions.MapResult[T1,T2,T3,TResult](ParserResult`1 result, Func`2 parsedFunc1, Func`2 parsedFunc2, Func`2 parsedFunc3, Func`2 notParsedFunc)
   at PapyrusCs.Program.Main(String[] args) in C:\projects\papyruscs-19426\PapyrusCs\Program.cs:line 46

Should this not be handled more gracefully, rather than an error exit?