The below statement in Editor. And this will execute successfully.
EDIT scott.emp WHERE e.sal > 1000;
But if the EDIT command line is seperated into 2 lines eg,
EDIT scott.emp
WHERE e.sal > 1000;
there will be a syntax error.

WORKAROUND :
1) Move the WHERE up to the first line. Keep EDIT statements to 1 line.
2) Edit is nothing more than a shortcut to write SELECT rowid, table.* FROM table.
Can setup an auto replace to replace "EDIT" with "select rowid, t.* from" and just need to add "table t".
Choose a simple alias that makes sense that can be use always for this command.
3) Remove the semi-colon from the statement and execute it with CTRL + Enter.
EDIT scott.emp
WHERE e.sal > 1000 ;
to
EDIT scott.emp
WHERE e.sal > 1000