The standard error menu for a (La)TeX run looks as follows:

Type <return> to proceed, S to scroll future error messages,
R to run without stopping, Q to run quietly,
I to insert something, E to edit your file,
1 or ... or 9 to ignore the next 1 to 9 tokens of input,
H for help, X to quit.

The E command opens the current input file in the an editor, which is TeXworks by default, and the input focus will be on the erroneous line.

The TeX editor can be configured by setting the MiKTeX configuration value editor, either in the configuration file, or via the environment variable MIKTEX_EDITOR.

First option: configuration file

You must edit the configuration file and add a line for the editor value:

C:\> initexmf --edit-config-file=miktex

Enter this line to configure Notepad++:

editor="C:\Program Files (x86)\Notepad++\notepad++.exe" -n%l "%f"

%l and %f are placeholders for the line number (where the error was detected) and the input file.

Second option: environment variable

C:\> set MIKTEX_EDITOR="C:\Program Files (x86)\Notepad++\notepad++.exe" -n%l "%f"