[BUG] Running script can cause console input to be executed #380

Bug summary: Running a script should not cause the text in the console's >>> to be executed after the script runs

Steps-to-reproduce: I set up a fresh N++ 8.7.8 (portable) and PS 3.0.21.0 to test the following (there may be simpler scenarios but this worked for me):

• Create a new script t.py with contents print('hello') followed by a line-ending, and save the script file
• Show the PS console window
• In the PS console window's >>> box, enter qqq (leaving the caret at the righthand end of that text) but do not press Enter key
• Using the mouse, click the Plugins menu in N++
• Click Python Script >
• Hover over the Scripts > menu item but do not click it; should now appear like this:

• Press the up arrow key on the keyboard once (the t script will become highlighted in the menu)
• Press the Enter key to execute the highlighted script
• Observe script output (good) but then also notice that the invalid code that was in the >>> box was also executed (BUG):