The output to the screen was:
A database query syntax error has occurred. This may indicate a bug in the software. The last attempted database query was:
(SQL query hidden)
from within function "". Database returned error "1146: Table 'test_wikidb.page' doesn't exist (localhost)".
This extension is the only one I have that executes at an onSave event. It was also the only one added prior to the last triggered onSave event.
Looking at the output shown above, the '.' in 'test_wikidb.page' should (with my configuration and prefixes) have been 'test_prefix' for a full table name of
'test_wikidb.test_prefix_page'