[tracer] Fix analytic derivative on Dirichlet boundaries

dumux/porousmediumflow/tracer/localresidual.hh

@@ -289,7 +289,8 @@ public:
                 DUNE_THROW(Dune::NotImplemented, "other reference systems than mass and molar averaged are not implemented");
 
             derivativeMatrices[scvf.insideScvIdx()][compIdx][compIdx] += (advDerivII + diffDeriv);
-            derivativeMatrices[scvf.outsideScvIdx()][compIdx][compIdx] += (advDerivIJ - diffDeriv);
+            if (!scvf.boundary())
+                derivativeMatrices[scvf.outsideScvIdx()][compIdx][compIdx] += (advDerivIJ - diffDeriv);
         }
     }