Update IntersectionType.php

Author: staabm

src/Type/IntersectionType.php

@@ -846,7 +846,7 @@ public function hasOffsetValueType(Type $offsetType): TrinaryLogic
 			if ($size instanceof IntegerRangeType && $size->getMin() !== null) {
 				$knownOffsets = IntegerRangeType::fromInterval(0, $size->getMin() - 1);
 			} elseif ($size instanceof ConstantIntegerType) {
-				$knownOffsets = IntegerRangeType::fromInterval(0, $size->getValue());
+				$knownOffsets = IntegerRangeType::fromInterval(0, $size->getValue() - 1);
 			} elseif ($this->isIterableAtLeastOnce()->yes()) {
 				$knownOffsets = new ConstantIntegerType(0);
 			} else {