Squiggly

Full definition of squiggly

Not straight; wavy.She didn't have a ruler, so she drew a squiggly line to highlight the main points.

(plural squigglies)

(computing, informal) A wavy underline used to indicate an error in text or code.

2007, Pariah S. Burke, Mastering InDesign CS3 for Print Design and Production (page 72)If you have dynamic spell checking enabled, your pamphlet will become a sea of red squigglies.
2008, Rick Leinecker, Vanessa L. Williams, Visual Studio 2008 All-In-One Desk Reference For Dummies (page 484)Coding errors have colored squigglies beneath them to indicate the kind of error. For example, syntax errors appear with red squigglies beneath them...
2010, James S. McKeown, Jim McKeown, Programming in Visual Basic 2010: The Very Beginner's Guide (page 75)The next blue squiggly is in the word Dimm. That should be an easy fix. Change it to Dim. Again, that swats two bugs with one fix.