Inside a Map there can not be a library node for fusion.

src/gt4py/next/program_processors/runners/dace_fieldview/transformations/map_fusion_helper.py

@@ -477,7 +477,7 @@ def partition_first_outputs(
                 # Certain nodes need more than one element as input. As explained
                 #  above, in this situation we assume that we can naturally decompose
                 #  them iff the node does not consume that whole intermediate.
-                #  Furthermore, it can not be a dynamic map range.
+                #  Furthermore, it can not be a dynamic map range or a library node.
                 intermediate_size = functools.reduce(lambda a, b: a * b, intermediate_desc.shape)
                 consumers = util.find_downstream_consumers(state=state, begin=intermediate_node)
                 for consumer_node, feed_edge in consumers:
@@ -488,6 +488,9 @@ def partition_first_outputs(
                         return None
                     if consumer_node is map_entry_2:  # Dynamic map range.
                         return None
+                    if isinstance(consumer_node, nodes.LibraryNode):
+                        # TODO(phimuell): Allow some library nodes.
+                        return None
 
                 # Note that "remove" has a special meaning here, regardless of the
                 #  output of the check function, from within the second map we remove
@@ -520,6 +523,9 @@ def partition_first_outputs(
                                 return None
                             if consumer_node is map_entry_2:  # Dynamic map range
                                 return None
+                            if isinstance(consumer_node, nodes.LibraryNode):
+                                # TODO(phimuell): Allow some library nodes.
+                                return None
                     else:
                         # Ensure that there is no path that leads to the second map.
                         after_intermdiate_node = util.all_nodes_between(