Do not return empty document symbols

The LSP spec does not allow returning empty document symbols with empty
name property.

See #870.

CHANGELOG.md

@@ -5,6 +5,12 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+
+### Fixed
+
+- Do not return symbols with empty names (e. g. sections without name) ([#870](https://github.com/latex-lsp/texlab/issues/870))
+
 ## [5.4.0] - 2023-03-12
 
 ### Added

src/features/symbol/types.rs

@@ -85,11 +85,13 @@ impl InternalSymbol {
         while i < container.len() {
             let symbol = &mut container[i];
 
-            if util::regex_filter::filter(
-                &symbol.name,
-                &config.allowed_patterns,
-                &config.ignored_patterns,
-            ) {
+            if !symbol.name.is_empty()
+                && util::regex_filter::filter(
+                    &symbol.name,
+                    &config.allowed_patterns,
+                    &config.ignored_patterns,
+                )
+            {
                 Self::filter(&mut symbol.children, config);
                 i += 1;
             } else {