script-launcher.applescript

set _Path to "<<enter path to your script folder here>>"  
set scriptLaunch to text returned of (display dialog "Enter name of script to run" default answer "" buttons "OK" default button "OK")  
if scriptLaunch contains "" then  
    error number -128  
else if scriptLaunch contains scriptLaunch then  
    try  
        set scriptRun to _Path & "/" & scriptLaunch & ".scpt"  
        run script scriptRun  
    on error  
        display alert "Your script failed to launch."  
    end try  
end if  

I combined both of your ideas: https://gist.github.com/dnnsmnstrr/c02ae3d5be5ab484b595cb8aea6cf65b