dom: Stop serialize from always reporting an error

The serialize function has an optional exception argument
to catch errors. One of our checks comes from normalising the
document and (at this point) this should only see namespace
errors. If not, we throw an internal error. However, the check
forgot that getException returns 0 if we are not in an exception
and turned the no exception case into an internal error. This is
fixed by checking if we are in an exceptional state before checking
the error code.

dom/m_dom_utils.f90

@@ -140,8 +140,11 @@ subroutine serialize(startNode, name, ex)
       call normalizeDocument(startNode, ex)
       if (present(ex)) then
         ! Only possible error should be namespace error ...
-        if (getExceptionCode(ex)/=NAMESPACE_ERR) then
-          if (getFoX_checks().or.FoX_INTERNAL_ERROR<200) then
+        ! but we should avoid turning an error of 0 into 
+        ! an internal error!
+        if (inException(ex)) then
+          if (getExceptionCode(ex)/=NAMESPACE_ERR) then
+            if (getFoX_checks().or.FoX_INTERNAL_ERROR<200) then
   call throw_exception(FoX_INTERNAL_ERROR, "serialize", ex)
   if (present(ex)) then
     if (inException(ex)) then
@@ -150,8 +153,8 @@ subroutine serialize(startNode, name, ex)
   endif
 endif
 
-        else
-          if (getFoX_checks().or.SERIALIZE_ERR<200) then
+          else
+            if (getFoX_checks().or.SERIALIZE_ERR<200) then
   call throw_exception(SERIALIZE_ERR, "serialize", ex)
   if (present(ex)) then
     if (inException(ex)) then
@@ -160,6 +163,7 @@ subroutine serialize(startNode, name, ex)
   endif
 endif
 
+          endif
         endif
       endif
     else

dom/m_dom_utils.m4

@@ -128,10 +128,14 @@ contains
       call normalizeDocument(startNode, ex)
       if (present(ex)) then
         ! Only possible error should be namespace error ...
-        if (getExceptionCode(ex)/=NAMESPACE_ERR) then
-          TOHW_m_dom_throw_error(FoX_INTERNAL_ERROR)
-        else
-          TOHW_m_dom_throw_error(SERIALIZE_ERR)
+        ! but we should avoid turning an error of 0 into 
+        ! an internal error!
+        if (inException(ex)) then
+          if (getExceptionCode(ex)/=NAMESPACE_ERR) then
+            TOHW_m_dom_throw_error(FoX_INTERNAL_ERROR)
+          else
+            TOHW_m_dom_throw_error(SERIALIZE_ERR)
+          endif
         endif
       endif
     else