findNext function family does not cross line boundaries correctly

expected: goes to the next occurrence
observed: when there are no more occurrences on this line it jumps to the next one but not the correct column.

tested with findNext, findNextFrom

Start by reproducing the reported behavior in the findNext and findNextFrom function family, focusing on searches that cross line boundaries. Trace how the next occurrence and column are selected; done means both functions reach the next occurrence at the correct column after the current line is exhausted.

Written by the indexing model from the issue text.