Update MutatingScope.php

Author: staabm

src/Analyser/MutatingScope.php

@@ -4308,7 +4308,14 @@ public function specifyExpressionType(Expr $expr, Type $type, Type $nativeType,
 		}
 
 		$scope = $this;
-		if ($expr instanceof Expr\ArrayDimFetch && $expr->dim !== null) {
+		if (
+			$expr instanceof Expr\ArrayDimFetch
+			&& $expr->dim !== null
+			&& !$expr->dim instanceof Expr\PreInc
+			&& !$expr->dim instanceof Expr\PreDec
+			&& !$expr->dim instanceof Expr\PostDec
+			&& !$expr->dim instanceof Expr\PostInc
+		) {
 			$dimType = $scope->getType($expr->dim)->toArrayKey();
 			if ($dimType instanceof ConstantIntegerType || $dimType instanceof ConstantStringType) {
 				$exprVarType = $scope->getType($expr->var);