Replacematcherror - catch exceptions and convert to internal error. (#424)

* Catch exceptions and convert to internal error.
We need to update the displayed message to incorporate a line number and text to be used for the issue.

* Cleanup exception handling/throwing.
Re-throw expected (or uncorrectable exceptions).
Provide Utils.getThrowable() to get the first (eldest) or last throwable in the chain.
Update tests to conform to FreeSpec protocol.

* Minor cleanup
Admit we've updated some deprecated ScalaTest methods.

1 files changed, 2 insertions, 2 deletions

diff --git a/src/main/scala/firrtl/transforms/CheckCombLoops.scala b/src/main/scala/firrtl/transforms/CheckCombLoops.scala
index bb2ffea9..98d6c3d1 100644
--- a/src/main/scala/firrtl/transforms/CheckCombLoops.scala
+++ b/src/main/scala/firrtl/transforms/CheckCombLoops.scala
@@ -71,9 +71,9 @@ class CheckCombLoops extends Transform {
           memport.expr match {
             case memref: WRef =>
               LogicNode(s.name,Some(memref.name),Some(memport.name))
-            case _ => throwInternalError
+            case _ => throwInternalError(Some(s"toLogicNode: unrecognized subsubfield expression - $memport"))
           }
-        case _ => throwInternalError
+        case _ => throwInternalError(Some(s"toLogicNode: unrecognized subfield expression - $s"))
       }
   }