refactor: reuse VariationNode.assertConsistency in DiffNode

Author: ibbem

src/main/java/org/variantsync/diffdetective/variation/diff/DiffNode.java

@@ -746,6 +746,9 @@ public static DiffNode<DiffLinesLabel> fromID(int id, String label) {
      * @throws AssertionError when an inconsistency is detected.
      */
     public void assertConsistency() {
+        // check that the projections are valid (i.e., node type specific consistency checks)
+        diffType.forAllTimesOfExistence(time -> this.projection(time).assertConsistency());
+
         // check consistency of children lists and edges
         for (final DiffNode<L> c : getAllChildren()) {
             Assert.assertTrue(isChild(c), () -> "Child " + c + " of " + this + " is neither a before nor an after child!");
@@ -779,22 +782,6 @@ public void assertConsistency() {
                 Assert.assertTrue(pb.isNon());
             }
         }
-
-        // Else and Elif nodes have an If or Elif as parent.
-        if (this.isElse() || this.isElif()) {
-            Time.forAll(time -> {
-                if (getParent(time) != null) {
-                    Assert.assertTrue(getParent(time).isIf() || getParent(time).isElif(), time + " parent " + getParent(time) + " of " + this + " is neither IF nor ELIF!");
-                }
-            });
-        }
-
-        // Only if and elif nodes have a formula
-        if (this.isIf() || this.isElif()) {
-            Assert.assertTrue(this.getFormula() != null, "If or elif without feature mapping!");
-        } else {
-            Assert.assertTrue(this.getFormula() == null, "Node with type " + getNodeType() + " has a non null feature mapping");
-        }
     }
 
     /**

src/main/java/org/variantsync/diffdetective/variation/diff/Projection.java

@@ -130,4 +130,9 @@ public Node getFormula() {
     public int getID() {
         return getBackingNode().getID();
     }
+
+    @Override
+    public String toString() {
+        return String.format("Projection(%s, %s)", time, getBackingNode());
+    }
 };