Panic in prepareExpression

[0x34d]

Bug Note:

file: fbclock/daemon/math_test.go, ptp/c4u/clock/math_test.go

func TestPrepareExpression_bug(t *testing.T) {

	prepareExpression(string("\\"))
}

run : go test -run TestPrepareExpression_bug $(pwd)/fbclock/daemon

backtrace

--- FAIL: TestPrepareExpression_bug (0.00s)
panic: runtime error: index out of range [1] with length 1 [recovered]
	panic: runtime error: index out of range [1] with length 1

goroutine 79 [running]:
testing.tRunner.func1.2({0x9a8900, 0xc000296660})
	/usr/lib/golang/src/testing/testing.go:1526 +0x24e
testing.tRunner.func1()
	/usr/lib/golang/src/testing/testing.go:1529 +0x39f
panic({0x9a8900, 0xc000296660})
	/usr/lib/golang/src/runtime/panic.go:884 +0x213
github.com/Knetic/govaluate.(*lexerStream).readCharacter(...)
	/home/0x34d/tools/go/pkg/mod/github.com/!knetic/govaluate@v3.0.0+incompatible/lexerStream.go:28
github.com/Knetic/govaluate.readUntilFalse(0xc000085d60, 0x0, 0x1, 0x1, 0xa044b0)
	/home/0x34d/tools/go/pkg/mod/github.com/!knetic/govaluate@v3.0.0+incompatible/parsing.go:272 +0x473
github.com/Knetic/govaluate.readTokenUntilFalse(0xc00000005c?, 0xc0000287a8?)
	/home/0x34d/tools/go/pkg/mod/github.com/!knetic/govaluate@v3.0.0+incompatible/parsing.go:249 +0x4c
github.com/Knetic/govaluate.readToken(0xc000085d60, {0x0, 0x1, 0x0, {0xc74ce0, 0x9, 0x9}}, 0x26?)
	/home/0x34d/tools/go/pkg/mod/github.com/!knetic/govaluate@v3.0.0+incompatible/parsing.go:193 +0x9f7
github.com/Knetic/govaluate.parseTokens({0xa62a90, 0x1}, 0x544873?)
	/home/0x34d/tools/go/pkg/mod/github.com/!knetic/govaluate@v3.0.0+incompatible/parsing.go:27 +0x31f
github.com/Knetic/govaluate.NewEvaluableExpressionWithFunctions({0xa62a90, 0x1}, 0x544840?)
	/home/0x34d/tools/go/pkg/mod/github.com/!knetic/govaluate@v3.0.0+incompatible/EvaluableExpression.go:99 +0x9f
github.com/facebook/time/fbclock/daemon.prepareExpression({0xa62a90?, 0x48ded7?})
	/home/0x34d/project/time/fbclock/daemon/math.go:198 +0x5a
github.com/facebook/time/fbclock/daemon.TestPrepareExpression_bug(0xc0002b0340?)
	/home/0x34d/project/time/fbclock/daemon/math_test.go:141 +0x47
testing.tRunner(0xc0002b11e0, 0xa045f8)
	/usr/lib/golang/src/testing/testing.go:1576 +0x10b
created by testing.(*T).Run
	/usr/lib/golang/src/testing/testing.go:1629 +0x3ea
exit status 2
FAIL	github.com/facebook/time/fbclock/daemon	0.010s