BenchmarkDotNet crash with `--join`

```
Unhandled exception. System.NullReferenceException: Object reference not set to an instance of an object. at BenchmarkDotNet.Reports.SummaryTable.SummaryTableColumn.<>c.<.ctor>b__24_1(String line) in BenchmarkDotNet.dll:token 0x6001730+0x0
at System.Linq.Enumerable.Max[TSource](IEnumerable`1 source, Func`2 selector) in System.Linq.dll:token 0x60000b4+0x5e at BenchmarkDotNet.Reports.SummaryTable.SummaryTableColumn..ctor(SummaryTable table, Int32 index, IColumn column) in BenchmarkDotNet.dll:token 0x60011fc+0xb3
at BenchmarkDotNet.Reports.SummaryTable.<>c__DisplayClass33_1.<.ctor>b__8(Int32 i) in BenchmarkDotNet.dll:token 0x6001204+0x0
at System.Linq.Enumerable.SelectRangeIterator`1.ToArray() in System.Linq.dll:token 0x60001d4+0x1e
at BenchmarkDotNet.Reports.SummaryTable..ctor(Summary summary, SummaryStyle style) in BenchmarkDotNet.dll:token 0x6000502+0x0
at BenchmarkDotNet.Reports.Summary.GetTable(SummaryStyle style) in BenchmarkDotNet.dll:token 0x60004d6+0x0
at BenchmarkDotNet.Reports.Summary..ctor(String title, ImmutableArray`1 reports, HostEnvironmentInfo hostEnvironmentInfo, String resultsDirectoryPath, String logFilePath, TimeSpan totalTime, CultureInfo cultureInfo, ImmutableArray`1 validationErrors) in BenchmarkDotNet.dll:token 0x60004cd+0x152
at BenchmarkDotNet.Reports.Summary.Join(List`1 summaries, ClockSpan clockSpan) in BenchmarkDotNet.dll:token 0x60004d4+0x85
at BenchmarkDotNet.Running.BenchmarkRunnerClean.Run(BenchmarkRunInfo[] benchmarkRunInfos) in BenchmarkDotNet.dll:token 0x6000417+0x314
at BenchmarkDotNet.Running.BenchmarkSwitcher.RunWithDirtyAssemblyResolveHelper(String[] args, IConfig config, Boolean askUserForInput) in BenchmarkDotNet.dll:token 0x6000448+0x131
at BenchmarkDotNet.Running.BenchmarkSwitcher.Run(String[] args, IConfig config) in BenchmarkDotNet.dll:token 0x6000447+0x6
at MicroBenchmarks.Program.Main(String[] args) in C:\gh\performance\src\benchmarks\micro\Program.cs:line 41
```

Running in src\benchmarks\micro directory:

`dotnet run -c Release -f net6.0 --join --filter *BenchI.Array2* *Bytemark.BenchLUDecomp* --coreRun C:\gh\runtime\artifacts\tests\coreclr\windows.x64.Release\Tests\Core_Root\CoreRun.exe C:\gh\runtime2\artifacts\tests\coreclr\windows.x64.Release\Tests\Core_Root\CoreRun.exe`

Note that I am specifying two filter expressions. If I remove one (e.g., use `--filter *BenchI.Array2* `), I don't see the crash.