[buehlmaier]

Release 2.0.6: argument validation, temp-file and reader cleanup, and join column order. Bumps project.clj and the README install snippets; the changes below were merged in #83–#86.

Bugs fixed

• A failed compute no longer deletes an existing output file: all argument validation now runs before the output file is touched (Validate compute and aggregate arguments before side effects #83).
• Unknown :select names are rejected with a TypeException listing them, on every dataframe type; joined frames used to throw a bare IndexOutOfBoundsException (Validate compute and aggregate arguments before side effects #83).
• num-worker is checked (integer, 1–8) for every compute path; it was only checked for group-by/aggregate, and 0 or negative values were accepted everywhere (Validate compute and aggregate arguments before side effects #83).
• aggregate checks that the number of new column names matches the number of aggregated columns (Validate compute and aggregate arguments before side effects #83).
• gb/mode returns tied modes sorted instead of in hash order (Validate compute and aggregate arguments before side effects #83).
• Temp group files under .clojask/grouped and .clojask/join are deleted when the compute that wrote them finishes, including on failure; they used to linger until the next compute (Delete temp group files when the compute that wrote them finishes #84).
• inner-join / outer-join without :select now keep the caller's column order (1_* first) in header, data and preview, even when the smaller-side heuristic swaps the inputs internally (Keep argument column order when a join swaps its sides #86).

Resource handling

• Depends on clojask-io 1.0.7, which closes its reader when the data is fully consumed and returns a :close function for early stops (Close abandoned CSV readers; bump clojask-io to 1.0.7 #85).
• dataframe construction opens its input once instead of three to four times, and closes it (Close abandoned CSV readers; bump clojask-io to 1.0.7 #85).
• preview, print-df and the pipeline error pre-check close their reader in a finally, also when the previewed pipeline throws (Close abandoned CSV readers; bump clojask-io to 1.0.7 #85).

Known, unchanged

• The bind extensions still open stat-only readers they never close.
• Readers abandoned when an Onyx job dies mid-compute are left to GC.

Local: lein test 52 tests / 198 assertions, 0 failures (JDK 25) on the code tree of this release.