another better error message for expressions
another better error message for expressions

ausonweng/csvfix,ausonweng/csvfix,mattgascoigne/csvfix,mcenirm/csvfix,ausonweng/csvfix,mattgascoigne/csvfix,jheusser/csvfix,mattgascoigne/csvfix,jheusser/csvfix,mcenirm/csvfix,mcenirm/csvfix,jheusser/csvfix