fix: don't break because of note not being None (support E_0594) (#384)

Author: hf-kklein

src/rebdhuhn/graph_conversion.py

@@ -4,7 +4,7 @@
 
 from typing import Dict, List, Literal, Optional, overload
 
-from networkx import DiGraph  # type:ignore[import-untyped]
+from networkx import DiGraph, isolates  # type:ignore[import-untyped]
 
 from rebdhuhn.models import (
     DecisionNode,
@@ -60,9 +60,7 @@ def _convert_sub_row_to_outcome_node(sub_row: EbdTableSubRow) -> Optional[Outcom
     if is_hinweis and sub_row.result_code is None and following_step:
         # We ignore Hinweise, if they are in during a decision process.
         return None
-    if sub_row.check_result.subsequent_step_number is not None and (
-        sub_row.result_code is not None or sub_row.note is not None
-    ):
+    if sub_row.check_result.subsequent_step_number is not None and sub_row.result_code is not None:
         raise OutcomeCodeAndFurtherStepError(sub_row=sub_row)
     if sub_row.result_code is not None or sub_row.note is not None and not is_cross_reference:
         return OutcomeNode(result_code=sub_row.result_code, note=sub_row.note)
@@ -221,6 +219,7 @@ def convert_table_to_graph(table: EbdTable) -> EbdGraph:
     if not any(table.rows):
         return convert_empty_table_to_graph(table.metadata)
     graph = convert_table_to_digraph(table)
+    _apply_workaround_to_issue_383(graph)
     graph_metadata = EbdGraphMetaData(
         ebd_code=table.metadata.ebd_code,
         chapter=table.metadata.chapter,
@@ -231,6 +230,16 @@ def convert_table_to_graph(table: EbdTable) -> EbdGraph:
     return EbdGraph(metadata=graph_metadata, graph=graph, multi_step_instructions=table.multi_step_instructions)
 
 
+def _apply_workaround_to_issue_383(graph: DiGraph) -> None:
+    """
+    removes isolated hinweis nodes which are not connected to the graph, e.g. 'Es gibt 1..n Treffer'...
+    Ideally we'd not create them at all, then we wouldn't have to remove them in a post processing step.
+    https://github.com/Hochfrequenz/rebdhuhn/issues/383
+    """
+    isolated = list(isolates(graph))
+    graph.remove_nodes_from(isolated)
+
+
 def convert_empty_table_to_graph(metadata: EbdTableMetaData) -> EbdGraph:
     """
     Converts an ebd section with no table to a graph to capture hints.