Panic when file ends with a block comment and no newline

[belak]

Describe the bug
When a file ends in a special quoted string and no newline, it will panic. A sample stack trace and test case has been included below.

% scc .
panic: runtime error: index out of range [649] with length 649

goroutine 98 [running]:
github.com/boyter/scc/processor.verifyIgnoreEscape(0xc000264000, 0xc000265200, 0xc000264900, 0xc000265b00, 0xc000266400, 0x7f2700237f00, 0x0, 0x0, 0x0, 0xc00019f5e0, ...)
	/private/tmp/scc-20191015-33901-1vdnpeq/scc-2.9.0/src/github.com/boyter/scc/processor/workers.go:352 +0xca
github.com/boyter/scc/processor.blankState(0xc0004a4000, 0x286, 0x288, 0x1, 0xc00051f4a0, 0x0, 0x0, 0xc0000ac2b8, 0x3, 0x8, ...)
	/private/tmp/scc-20191015-33901-1vdnpeq/scc-2.9.0/src/github.com/boyter/scc/processor/workers.go:317 +0x10f
github.com/boyter/scc/processor.CountStats(0xc0004a4000)
	/private/tmp/scc-20191015-33901-1vdnpeq/scc-2.9.0/src/github.com/boyter/scc/processor/workers.go:459 +0xe38
github.com/boyter/scc/processor.fileProcessorWorker.func1(0xc0000a6120, 0xc000236000, 0xc0000a6180, 0xc000236010)
	/private/tmp/scc-20191015-33901-1vdnpeq/scc-2.9.0/src/github.com/boyter/scc/processor/workers.go:743 +0x243
created by github.com/boyter/scc/processor.fileProcessorWorker
	/private/tmp/scc-20191015-33901-1vdnpeq/scc-2.9.0/src/github.com/boyter/scc/processor/workers.go:709 +0xb0

To Reproduce

In theory this should match the line numbers for if the file ends in a newline, but that doesn't seem to be counted the same and I really didn't want to figure that out. I've included a regression test.

func TestCountStatsIssue(t *testing.T) {
	ProcessConstants()
	fileJob := FileJob{
		Language: "Python",
	}

	fileJob.Content = []byte(`"""
hello there! how's it going?
"""`)

	CountStats(&fileJob)

	if fileJob.Lines != 2 {
		t.Errorf("Expected 2 lines got %d", fileJob.Lines)
	}

	if fileJob.Code != 1 {
		t.Errorf("Expected 1 lines got %d", fileJob.Code)
	}

	if fileJob.Comment != 1 {
		t.Errorf("Expected 1 lines got %d", fileJob.Comment)
	}

	if fileJob.Blank != 0 {
		t.Errorf("Expected 0 lines got %d", fileJob.Blank)
	}
}

Expected behavior
For scc to not panic

Desktop (please complete the following information):

• OS: macOS
• Version: 2.9.0 (79458d6)

[boyter]

Quality bug report and PR @belak
Already merged. Ill push out a 2.9.1 soon to ensure nobody gets this case.

[boyter]

Release pushed out. Thanks so much for reporting this and providing PR.

[belak]

Yep, no problem! I ran across this project yesterday and decided to try it against our repos... which ran into this bug. Seemed like a simple fix. :) Thanks for the quick response!