Improve parse tree errors (#207)

Author: pokey

src/extension.ts

@@ -25,20 +25,7 @@ export async function activate(context: vscode.ExtensionContext) {
     throw new Error("Depends on pokey.parse-tree extension");
   }
 
-  const { getNodeAtLocation: getNodeAtLocationImpl } =
-    await parseTreeExtension.activate();
-
-  const getNodeAtLocation = (location: vscode.Location) => {
-    try {
-      return getNodeAtLocationImpl(location);
-    } catch (error) {
-      const document = vscode.window.activeTextEditor?.document;
-      if (document?.uri === location.uri) {
-        throw Error(`Language '${document.languageId}' is not implemented yet`);
-      }
-      throw error;
-    }
-  };
+  const { getNodeAtLocation } = await parseTreeExtension.activate();
 
   var isActive = vscode.workspace
     .getConfiguration("cursorless")

src/languages/index.ts

@@ -31,16 +31,23 @@ export function getNodeMatcher(
   includeSiblings: boolean
 ): NodeMatcher {
   const matchers = languageMatchers[languageId];
+
   if (matchers == null) {
-    throw Error(`Language '${languageId}' is not implemented yet`);
+    throw Error(
+      `Language '${languageId}' is not implemented yet; See https://github.com/pokey/cursorless-vscode/blob/master/docs/adding-a-new-language.md`
+    );
   }
+
   const matcher = matchers[scopeType];
+
   if (matcher == null) {
     return notSupported;
   }
+
   if (includeSiblings) {
     return matcherIncludeSiblings(matcher);
   }
+
   return matcher;
 }
 

src/processTargets.ts

@@ -263,16 +263,16 @@ function transformSelection(
       return [{ selection, context: {} }];
 
     case "containingScope":
-      let node: SyntaxNode | null = context.getNodeAtLocation(
-        new Location(selection.editor.document.uri, selection.selection)
-      );
-
       const nodeMatcher = getNodeMatcher(
         selection.editor.document.languageId,
         modifier.scopeType,
         modifier.includeSiblings ?? false
       );
 
+      let node: SyntaxNode | null = context.getNodeAtLocation(
+        new Location(selection.editor.document.uri, selection.selection)
+      );
+
       while (node != null) {
         const matches = nodeMatcher(selection, node);
         if (matches != null) {