Don't silently eat a certain class of analyzer-thrown exceptions

If an analyzer threw an exception, we generate a message that tells
you what diagnostic IDs the analzyer produces, so you know what to
disable so you can work around the analyzer. If the analyzer then also
were to throw exceptions while we ask it for it's SupportedDiagnostics,
we were eating that exception. This includes that as well.

src/Compilers/Core/Portable/DiagnosticAnalyzer/AnalyzerExecutor.cs

@@ -1657,9 +1657,9 @@ private static string CreateDisablingMessage(DiagnosticAnalyzer analyzer)
                     diagnosticIds = diagnosticIds.Add(diagnostic.Id);
                 }
             }
-            catch (Exception)
+            catch (Exception ex)
             {
-                // Intentionally empty
+                return string.Format(CodeAnalysisResources.AnalyzerDriverThrowsDescription, ex.CreateDiagnosticDescription());
             }
 
             if (diagnosticIds.IsEmpty)