light: ensure trust level is strictly less than 1 (#6447)

light/verifier.go

@@ -167,10 +167,10 @@ func Verify(
 
 // ValidateTrustLevel checks that trustLevel is within the allowed range [1/3,
 // 1]. If not, it returns an error. 1/3 is the minimum amount of trust needed
-// which does not break the security model.
+// which does not break the security model. Must be strictly less than 1.
 func ValidateTrustLevel(lvl tmmath.Fraction) error {
 	if lvl.Numerator*3 < lvl.Denominator || // < 1/3
-		lvl.Numerator > lvl.Denominator || // > 1
+		lvl.Numerator >= lvl.Denominator || // >= 1
 		lvl.Denominator == 0 {
 		return fmt.Errorf("trustLevel must be within [1/3, 1], given %v", lvl)
 	}