Exception when looking up symbols of empty keywords

[FoamScience]

Describe the bug The following OpenFOAM file will cause the LSP server to throw an exception when attempting to get document symbols

fluxRequired
{
   p;
}

Expected behavior Report fluxxRequired.p as a symbol

Desktop (please complete the following information):

• OS: Ubuntu 22 (irrelevant)
• Text Editor or Editor: Neovim
• Version 0.3.2