nodes: add several asserts to make debugging some weird internal issues easier

compiler/nodes.py

@@ -25,6 +25,7 @@ class Node:
 
     @functools.cache
     def location(self) -> SourceLocation:
+        assert len(self._values()) > 0
         locations = [v.location() for v in self._values()]
         begin = min([loc.begin for loc in locations])
         end = max([loc.end for loc in locations])
@@ -271,6 +272,7 @@ class Statement(Node):
             self.pseudo_nodes = pseudo_nodes
 
     def _values(self) -> list[Node | Any]:
+        assert len(self.nodes) + len(self.pseudo_nodes) > 0
         return self.nodes + self.pseudo_nodes
 
     def intermediate_representation(self) -> list[ir.IRItem]: