Warning instead of error?
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philkime
Consider the LaTeX input file
\documentclass{article}
\usepackage[backend=biber]{biblatex}
\begin{document}
\end{document}
If Biber is run on the corresponding BCF file it stops with an error since no bibliographic resources have been specified. Issuing an equivalent warning message might be more appropriate, though. At any rate, life would become easier for Latexmk and friends.
Good point. This has now been changed in the latest biber 1.0 dev beta. Note you'll need to be using the latest biblatex 2.0 beta with this.