Wie finde ich die Bedeutung von Fehlermeldungen? Gibt es systematische Fehlerverzeichnisse?

! Output loop---100 consecutive dead cycles.
\break

 ->\penalty -\@M

l.61 \end{theindex}

I've concluded that your \output is awry; it never does a
\shipout, so I'm shipping \box255 out myself. Next time
increase \maxdeadcycles if you want me to be more patient!

[29
! Undefined control sequence.
\reserved@a ->\@nil

l.61 \end{theindex}

The control sequence at the end of the top line
of your error message was never \def'ed. If you have
misspelled it (e.g., `\hobx'), type `I' and the correct
spelling (e.g., `I\hbox'). Otherwise just continue,
and I'll forget about whatever was undefined.

! Use of \@BOOKMARK doesn't match its definition.
\@ifnextchar ...eserved@d =#1\def \reserved@a {#2}
                                                  \def \reserved@b {#3}\futu...
l.61 \end{theindex}

If you say, e.g., `\def\a1{...}', then you must always
put `1' after `\a', since control sequence names are
made up of letters only. The macro here has not been
followed by the required stuff, so I'm ignoring it.

! Undefined control sequence.
<argument> \@@BOOKMARK 
                       [1][-]
l.61 \end{theindex}

The control sequence at the end of the top line
of your error message was never \def'ed. If you have
misspelled it (e.g., `\hobx'), type `I' and the correct
spelling (e.g., `I\hbox'). Otherwise just continue,
and I'll forget about whatever was undefined.

Runaway argument?
{\ila@prologueplus }\reserved@b \fi \fi \reserved@c 
! Paragraph ended before \mult@@cols was complete.
<to be read again> 
                   \par 
l.61 \end{theindex}

I suspect you've forgotten a `}', causing me to apply this
control sequence to too much text. How can we recover?
My plan is to forget the whole thing and hope for the best.

! Undefined control sequence.
\GenericError  ...                                
                                                    #4  \errhelp \@err@     ...
l.61 \end{theindex}

The control sequence at the end of the top line
of your error message was never \def'ed. If you have
misspelled it (e.g., `\hobx'), type `I' and the correct
spelling (e.g., `I\hbox'). Otherwise just continue,
and I'll forget about whatever was undefined.

! Undefined control sequence.
\GenericError  ...                                
                                                  \let \@err@               ...
l.61 \end{theindex}