Language Server: Provide more detailed error message on syntax error.
Language Server: Provide more detailed error message on syntax error.

While we only have somewhat poor error description from yacc, provide
at least what we know from the rejected token.

Signed-off-by: Henner Zeller <e393654266408b751fd8ad27b99ca78813d38e23@google.com>

chipsalliance/verible,chipsalliance/verible,chipsalliance/verible,chipsalliance/verible,chipsalliance/verible