core: hack missing post path traction and grades

The path's context only extends until the end of the path. Hence, for an SvL located further along, the tractive effort and the slopes are missing. In this commit, we hack it to make it work, but we could potentially extend the path's context so it goes until the last SvL, if it breaks nothing.

Signed-off-by: Erashin <[email protected]>

core/envelope-sim/src/main/java/fr/sncf/osrd/envelope_sim/EnvelopeSimPath.java

@@ -111,6 +111,10 @@ public double getMinGrade(double begin, double end) {
         // TODO: Optimise method by adding in a cache.
         int indexBegin = getIndexBeforePos(begin);
         int indexEnd = getIndexBeforePos(end);
+        // TODO: Remove if we extend path properties until last SvL > path.length.
+        if (indexBegin == indexEnd && indexBegin == gradePositions.length - 1)
+            // Take last grade value in this case
+            return gradeValues[gradeValues.length - 1];
         var lowestGradient = gradeValues[indexBegin];
         for (int i = indexBegin; i < indexEnd; i++) {
             var grad = gradeValues[i];