fix(go): return nil instead of panic when AST node has invalid position (#197)

* fix(go): return nil instead of panic when AST node has invalid position

When parsing files with compilation errors, AST nodes can have End offset
smaller than Pos offset, causing slice bounds out of range panic.

Author: wzekin

.github/workflows/go-test.yml

@@ -42,7 +42,7 @@ jobs:
           components: rust-analyzer
 
       - name: Install gopls
-        run: go install golang.org/x/tools/gopls@latest
+        run: go install golang.org/x/tools/gopls@v0.16.2
 
       - name: Run all tests
         run: go test ./lang/... -skip '${{ env.SKIPPED_TESTS }}'

lang/golang/parser/ctx.go

@@ -257,6 +257,7 @@ func GetRawContent(fset *token.FileSet, file []byte, node ast.Node, collectComme
 			funcName = fn.Name.Name
 		}
 		fmt.Fprintf(os.Stderr, "end < begin, file: %s, function: %s, possibly because file compilation failed\n", pos.Filename, funcName)
+		return nil
 	}
 	doc.Write(file[pos.Offset:endPos.Offset])
 	return doc.Bytes()