Surrounding pairs: Fall back to text based algorithm when error node is detected.

packages/cursorless-engine/src/processTargets/modifiers/surroundingPair/index.ts

@@ -99,6 +99,18 @@ function processSurroundingPairCore(
   try {
     node = languageDefinitions.getNodeAtLocation(document, range);
 
+    // Error nodes are unreliable and should be ignored. Fall back to text based
+    // algorithm.
+    if (nodeHasError(node)) {
+      return findSurroundingPairTextBased(
+        editor,
+        range,
+        null,
+        delimiters,
+        scopeType,
+      );
+    }
+
     textFragmentExtractor = getTextFragmentExtractor(document.languageId);
   } catch (err) {
     if ((err as Error).name === "UnsupportedLanguageError") {
@@ -148,3 +160,22 @@ function processSurroundingPairCore(
     scopeType,
   );
 }
+
+function nodeHasError(node: SyntaxNode, includeChildren = false): boolean {
+  if (nodeIsError(node)) {
+    return true;
+  }
+  if (includeChildren) {
+    if (node.children.some(nodeIsError)) {
+      return true;
+    }
+  }
+  if (node.parent != null) {
+    return nodeHasError(node.parent, true);
+  }
+  return false;
+}
+
+function nodeIsError(node: SyntaxNode): boolean {
+  return node.type === "ERROR";
+}

packages/cursorless-vscode-e2e/src/suite/fixtures/recorded/surroundingPair/parseTree/python/clearPair5.yml

@@ -0,0 +1,22 @@
+languageId: python
+command:
+  version: 5
+  spokenForm: clear pair
+  action: {name: clearAndSetSelection}
+  targets:
+    - type: primitive
+      modifiers:
+        - type: containingScope
+          scopeType: {type: surroundingPair, delimiter: any}
+  usePrePhraseSnapshot: true
+initialState:
+  documentContents: "def funk(words:list<str>):"
+  selections:
+    - anchor: {line: 0, character: 20}
+      active: {line: 0, character: 20}
+  marks: {}
+finalState:
+  documentContents: "def funk(words:list):"
+  selections:
+    - anchor: {line: 0, character: 19}
+      active: {line: 0, character: 19}