Merge pull request #14693 from overleaf/unknown-document-environment

Set EnvName as optional in Environment definition

GitOrigin-RevId: feb048199737108734df45fd4a057d932a6bf785

services/web/frontend/js/features/source-editor/lezer-latex/latex.grammar

@@ -613,9 +613,9 @@ EnvNameGroup<name> {
 }
 
 Environment[@isGroup="$Environment"] {
-    BeginEnv<EnvName>
+    BeginEnv<EnvName?>
     Content<Text>
-    EndEnv<EnvName>
+    EndEnv<EnvName?>
 }
 
 Group<GroupContent> {